Golf ball incorporating steep hardness gradient and high compression thermoset rubber core

ABSTRACT

A golf ball comprising a core comprising at least one layer that consists of a mixture of a plurality of synthetic flocks and a thermoset rubber composition. The plurality of synthetic flocks has a melting temperature that is greater than a mixing temperature at which the mixture is formed. Additionally, the at least one layer comprises an outer surface having an outer surface hardness of about 80 Shore C or greater and the outer surface hardness is greater than a center hardness of a geometric center of the core by at least 20 Shore C. A cover having at least one layer is disposed about the core. The synthetic flocks may be included in the mixture in an amount of from about 0.5 parts to about 15 parts of the total mixture. Examples of suitable synthetic flocks include nylon, polyester, polypropylene, aramid, or acrylic flocks, or combinations thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending, co-assignedU.S. patent application Ser. No. 14/021,818, filed on Sep. 9, 2013, nowallowed, which is a continuation-in-part of co-assigned U.S. patentapplication Ser. No. 13/309,085 filed on Dec. 1, 2011, now U.S. Pat. No.8,529,378, which is divisional of U.S. patent application Ser. No.12/143,879, filed on Jun. 23, 2008, now U.S. Pat. No. 8,070,626, whichis a continuation-in-part of U.S. patent application Ser. No.11/707,493, filed on Feb. 16, 2007, now U.S. Pat. No. 7,722,483, theentire disclosure of each of which is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Golf balls incorporating high compression, steep hardness gradientthermoset rubber cores with controlled resilience.

BACKGROUND OF THE INVENTION

Golf balls are made in a variety of constructions and compositions. Inrecent years, virtually all golf balls are of a solid construction,generally including a solid core encased by a cover, both of which canhave multiple layers, such as a dual core having a solid center and anouter core layer, or a multi-layer cover having an inner and outer coverlayer. Examples of golf ball materials range from balata topolybutadiene, ionomer resins, polyurethanes, polyureas, and/orpolyurethane/polyurea hybrids. Typically, outer layers are formed aboutthe spherical outer surface of an inner golf ball component viacompression molding, casting, or injection molding.

Golf ball cores are often formed at least in part from a thermosetrubber composition with polybutadiene as the base rubber. The cores areusually heated and crosslinked to create a core having certainpre-determined characteristics, such as compression or hardness, whichresult in a golf ball having the properties for a particular group ofplayers, whether it be professionals, low-handicap players, ormid-to-high handicap golfers. From the perspective of a golf ballmanufacturer, it is desirable to have cores exhibiting a wide range ofproperties, such as resilience, durability, spin, and “feel,” becausethis enables the manufacturer to make and sell golf balls suited todiffering levels of ability.

Therefore, golf ball manufacturers continuously experiment with golfball constructions and material formulations in order to target andimprove aerodynamic and/or inertial properties and achieve desired feelwithout sacrificing durability. For example, spin performance can beenhanced by employing a golf ball construction using a steep gradientcore (solid or multi-piece), meaning the hardness (JIS C or Shore D)increases considerably from the center point to the surface of the core.Steep hardness gradients usually produce a lower driver spin while stillmaintaining the desired approach and wedge spin. Meanwhile, betterplayers often like higher compression golf balls—having faster swingspeeds, they are capable of compressing the ball and still achieve thedistance while gaining better control.

Steep hardness gradient cores may be created by employing a dual coreconstruction wherein the inner core layer and an outer core layer aremade from rubber formulations having differing physical properties. Forexample, a softer, less stiff inner core layer may be surrounded by ahard, stiffer outer core layer. The hardness and stiffness of eachthermoset layer and the overall gradient of the core are conventionallymodified by adding or subtracting coagents such as ZDA, ZDMA, HVA etc.;by adjusting the amount or type of peroxide crosslinker used; byincorporating chemical additives such as antioxidants, organosulfurs,etc.; and/or by changing cure time/temperature. However, suchmodifications can cause durability issues, such as crack propagation,which can result from changes in the crosslink density of the curedthermoset rubber material.

Yet, it can also be difficult to increase the compression of arubber-based core by adding fillers without meanwhile also undesirablyreducing resiliency/coefficient of restitution (CoR) of the corematerial. For example, poor coupling can occur between the filler andthe rubber which can decrease the core's ability to rebound. Generally,a lower core CoR is undesirable, given that a golf ball's principalsource of resiliency is typically in the rubber-based core, and high CoRvalues (i.e., closer to 1) will favorably correspond to a golf ballhaving a higher initial velocity and ultimately, greater overalldistance.

And adding fillers that are known for increasing both compression andCoR are equally undesirable, since rubber-based cores are typicallyalready abundantly resilient—unlike ionomeric layers, for example, whichcan protect the rubber core but generally lack resilience withoutcombining ionomeric matrix material with some type ofresilience-improving additive.

Accordingly, there is a need for durable golf balls incorporating highcompression, steep hardness gradient rubber-based cores with controlledresilience/CoR that can be manufactured efficiently and costeffectively. The present inventive golf balls and methods of making sameaddress and solve these needs.

SUMMARY OF THE INVENTION

Advantageously, a golf ball of the invention incorporates a highcompression thermoset rubber core having a high outer surface hardness,steep hardness gradient from geometric center to the outer surface, andcontrolled resilience/CoR (not substantially decreasing or increasingCoR).

In one embodiment, a golf ball of the invention comprises a corecomprising an inner core layer and an outer core layer; wherein theouter core layer consists of a mixture of a plurality of syntheticflocks and a first thermoset rubber composition. The plurality ofsynthetic flocks has a melting temperature that is greater than a mixingtemperature at which the mixture is formed. The inner core layer doesnot contain said flocks.

The outer core layer comprises an outer surface having an outer surfacehardness of about 80 Shore C or greater; and the outer surface hardnessis greater than a center hardness of a geometric center of the core byat least 20 Shore C. In one alternative embodiment, the outer surfacehardness is about 90 Shore C or greater and is greater than the centerhardness by greater than 30 Shore C. Meanwhile, a cover comprising oneor more layers is disposed about the core.

The synthetic flocks may be included in the mixture in an amount of fromabout 0.5 parts to about 15 parts of the total mixture. Non-limitingexamples of suitable synthetic flocks include nylon, polyester,polypropylene, aramid, or acrylic flocks, or combinations thereof. Theplurality of flocks is the only thermoplastic ingredient in the mixture.

In one embodiment, the first thermoset rubber composition comprisespolybutadiene. In another embodiment, the first thermoset rubbercomposition comprises a blend of polybutadiene and at least one ofpolyoctenemer, natural rubber, ethylene propylene diene monomer (EPDM),cis-polyisoprene, trans-polyisioprene, and/or styrene-butadiene rubber(SBR).

In yet another embodiment, the first thermoset rubber compositionfurther comprises at least one of zinc oxide, reactive coagent(s),peroxide(s), soft and fast agent(s), fatty acid(s)/fatty acid salt(s),inorganic filler(s), antioxidant(s), and antiozonants.

In one embodiment, the outer core layer has a compression of greaterthan 72. In another embodiment, the outer core layer has a compressionof at least 75.

In one embodiment, the outer core layer surrounds and is adjacent to theinner core layer.

In one embodiment, the inner core layer consists of a thermosetcomposition. For example, the thermoset composition may in oneembodiment be a second thermoset rubber composition different than thefirst thermoset rubber composition.

Alternatively, the inner core layer may consist of a thermoplasticcomposition. In one embodiment, the thermoplastic composition comprisesan ionomer. In other embodiments, the thermoplastic composition maycomprise a polyether-ester, a polyester-amide, or blends thereof.

In another embodiment, an intermediate core layer is disposed betweenthe inner core layer and the outer core layer. In one embodiment, theintermediate layer comprises a thermoplastic composition.

Meanwhile, in one embodiment, the cover may comprise an inner coverlayer disposed about the outer core layer and comprising an ionomericmaterial and having a first hardness; and an outer cover layer disposedabout the inner cover layer and comprising a polyurea or a polyurethaneand having a second hardness less than the first.

In one embodiment, each of the plurality of synthetic flocks has alength in the range of about 0.5 mm (500 μm or 0.02 inches) to about 2.0mm (2000 μm or 0.08 inches). In a particular embodiment, each of theplurality of synthetic flocks has a length in the range of about 0.5 mm(500 μm or 0.02 inches) to about 1.016 mm (1016 μm or 0.04 inches).

In a different embodiment, a golf ball of the invention comprises a corecomprising at least one layer that consists of a mixture of a pluralityof synthetic flocks and a thermoset rubber composition. The plurality ofsynthetic flocks has a melting temperature that is greater than a mixingtemperature at which the mixture is formed.

Additionally, the at least one layer comprises an outer surface havingan outer surface hardness of about 80 Shore C or greater, and the outersurface hardness is greater than a center hardness of a geometric centerof the core by at least 20 Shore C. A cover having at least one layer isdisposed about the core.

A golf ball of the invention may be made, for example, by: (i) providingan inner core layer; (ii) forming an outer core layer that consists of amixture of a plurality of synthetic flocks and a thermoset rubbercomposition about the inner core layer; wherein the plurality syntheticflocks have a melting temperature that is greater than a mixingtemperature at which the mixture is formed; and wherein the plurality ofsynthetic flocks are included in the mixture in an amount such that theouter core layer comprises an outer surface having an outer surfacehardness of about 80 Shore C or greater and the outer surface hardnessis greater than a center hardness of a geometric center of the core byat least 20 Shore C; and (iii) forming at least one cover layer aboutthe outer core layer.

Embodiments are also envisioned wherein the method further comprisesforming at least one intermediate core layer about the inner core layerand forming the outer core layer about the intermediate core layer. Oneor more intermediate layers may be formed between the outer core layerand at least one cover layer.

Alternatively, the method for making a golf ball of the invention maycomprise: (i) forming a core by providing at least one layer consistingof a mixture of a plurality of synthetic flocks and a thermoset rubbercomposition; wherein the plurality of synthetic flocks has a meltingtemperature that is greater than a mixing temperature at which themixture is formed; and wherein the synthetic flocks are included in themixture in an amount such that the core has an outer surface having anouter surface hardness of about 80 Shore C or greater; and wherein theouter surface hardness is greater than a center hardness of a geometriccenter of the core by at least 20 Shore C; and (ii) forming at least onecover layer about the outer core layer.

Although it preferred the core has at least two layers, embodiments areenvisioned wherein the core might entirely consist of the mixture.

In some embodiments, the method may further comprise forming at leastone intermediate layer about the core and then forming the at least onecover layer about the at least one intermediate layer.

DETAILED DESCRIPTION

A golf ball of the invention is an improved steep positive hardnessgradient multi-piece golf ball incorporating at least one outer corelayer that consists of a mixture of a thermoset rubber composition and aplurality of synthetic flocks such as nylon or polyester to enhanceproperties such as increasing compression and surface hardness withoutcausing crack propagation in the cured core or reducing resilience/CoRsignificantly. Meanwhile, the inner core layer does not contain saidflocks. Greater physical property differences can be achieved betweenthe outer core layer and inner core layer without sacrificing orotherwise substantially changing core resiliency and meanwhile providingincreased design flexibility with controlled manufacturing costs.

In this regard, four inventive spheres Ex. 1, Ex. 2, Ex. 3, and Ex. 4were formed and compared with three comparative spheres Comp. Ex. 1,Comp. Ex. 2 and Comp. Ex. 3. The exact formulations for inventive coresEx. 1, Ex. 2, Ex. 3, and Ex. 4 and comparative cores Comp. Ex. 1, Comp.Ex. 2 and Comp. Ex. 3 are as follows:

TABLE I INGRE- Comp. Comp. Comp. DIENTS PHR EX. 1 EX. 2 EX. 3 EX. 4 EX.1 EX. 2 EX. 3 Polybutadiene 100 100 100 100 100 100 100 ZnO 5 5 5 5 5 55 ZDA 30 30 30 30 30 30 30 ZnPCTP 0.7 0.7 0.7 0.7 0.7 0.7 0.7 Dicumyl0.5 0.5 0.5 0.5 0.5 0.5 0.5 Peroxide Polyester 2 5 0 0 0 0 0 Flock¹Nylon Flock² 0 0 2 5 0 0 0 Cotton Flock³ 0 0 0 0 0 2 5 Barium Sulfatevaried to adjust weight ¹Akroflock PW #31 White Polyester, availablefrom Akrochem Corporation. ²Akroflock ND 109 Dark Nylon, available fromAkrochem Corporation. ³Akroflock CDV - 2 Dark Cotton, available fromAkrochem Corporation.

All seven spheres included the same rubber matrix set forth in Table I.Inventive spheres Ex. 1, Ex. 2, Ex. 3, and Ex. 4 were formed by mixingthis rubber matrix with synthetic flocks (polyester or nylon), whereascomparative core Comp. Ex. 1 was formed solely from the rubber matrixingredients, and comparative spheres Comp. Ex. 2 and Comp. 3 includednatural flocks (cotton) rather than synthetic flocks. The ingredientsfor each of the seven spheres were compounded and mixed in a Brabendermixer.

The resulting rubber compositions were molded for 11 minutes at 350° F.and then subjected to centerless grinding to a diameter of 1.550″.Subsequently, all finished spheres were evaluated for hardness,compression and CoR. The test results are set forth in TABLE II asfollows:

TABLE II Comp. Comp. Comp. Property EX. 1 EX. 2 EX. 3 EX. 4 EX. 1 EX. 2EX. 3 Compression 76 84 75 82 72 65 62 Surface 82.5 83.5 82.8 84.0 82.081.5 79.9 Hardness Shore C Center 60.5 59.7 58.2 55.0 57.3 61.1 62.0Hardness Shore C Shore C Gradient 22.0 23.8 24.6 29.0 24.7 20.4 17.9 CoR0.811 0.806 0.811 0.808 0.813 0.804 0.789

As is shown in TABLE II, all of cured inventive spheres Ex. 1, Ex. 2,Ex. 3, Ex. 4, incorporating synthetic flocks, have high outer surfacehardnesses and desirably steep Shore C hardness gradients as well asfavorably higher compressions than each of the three comparative coresComp. Ex. 1 (no flocks), Comp. Ex. 2 (2 phr of natural flock (cotton)flocks) and Comp. Ex. 3 (5 phr of natural (cotton) flocks). Andmeanwhile, resulting inventive spheres Ex. 1, Ex. 2, Ex. 3, Ex. 4 alsoadvantageously have controlled CoRs not substantially different than theCoRs of comparative spheres Comp. Ex. 1 and Comp. Ex. 2.

In further contrast, comparative core Comp. EX. 3 containing 5 phrcotton flock has a lower outer surface Shore C hardness than all sixother spheres as well as an undesirably lower Shore C hardness gradientof less than 20 (17.9), with its compression and CoR also beingsubstantially below that of not only comparative core Comp. EX. 1, whichis formed solely of the rubber matrix, but also less than those of allfive other spheres.

Accordingly, inventive outer core layer materials Ex. 1, Ex. 2, Ex. 3,and Ex. 4, formed from a mixture of a rubber matrix and syntheticflocks, advantageously have a high outer surface hardness, a steephardness gradients of at least 20, and higher compressions over theother rubber matrixes—whether containing no flocks or natural cottonflocks—meanwhile without sacrificing or otherwise substantially changingcore resiliency or CoR. In this regard, non-substantial CoR differencessuch as between outer core layer materials Ex. 1, Ex. 2, Ex. 3, and Ex.4 compared with Comp. EX. 1 (not including flock) can generally beaddressed by targeting the resilience of outer golf ball layers (e.g.inner cover layers) to achieve a particular desired overall golf ballCoR. And meanwhile, golf balls of the invention incorporating corematerials Ex. 1, Ex. 2, Ex. 3, and Ex. 4 would not typically be subjectto increased crack propagation.

A golf ball of the invention may therefore comprise a multi-layer coreand one or more cover layers. For example, a soft inner core layer maybe surrounded by at least one stiff outer core layer that is formed fromthe thermoset rubber composition mixed with a plurality of syntheticfibers such as nylon, polyester, polypropylene, aramid, acrylic flocks,or combinations thereof. The synthetic flocks may be mixed with theingredients of the rubber matrix (thermoset rubber composition) in anamount of from about 0.5 parts to about 15 parts of the total mixture orfrom about 1 part to about 10 parts of the total mixture or from about 2parts to about 7 parts of the total mixture or from about 2 parts toabout 5 parts of the total mixture or from about 1 parts to about 5parts of the total mixture. Once again, the plurality of flocks is theonly thermoplastic ingredient in the mixture. And embodiments areenvisioned wherein at least some of the flocks are surface-activated inorder to improve compatibility, dispersibility, and/or durability.

In one embodiment, each of the plurality of synthetic flocks has alength in the range of about 0.5 mm (500 μm or 0.02 inches) to about 2.0mm (2000 μm or 0.08 inches). In a particular embodiment, each of theplurality of synthetic flocks has a length in the range of about 0.5 mm(500 μm or 0.02 inches) to about 1.016 mm (1016 μm or 0.04 inches).Embodiments are also envisioned wherein each of the plurality ofsynthetic flocks has a length in the range of about 0.1 mm (100 μm or0.004 inches) to about 5.0 mm (5000 μm or 0.2 inches).

The inner core layer(s) can be formed from a thermoplastic or thermosetmaterial. In one embodiment, the inner core layer comprises a thermosetrubber composition having different physical properties (lowerhardness/lower compression/lower modulus) than the outer core layer.

The outer core layer should have a surface hardness of about 80 Shore Cor greater, more preferably about 85 Shore C or greater, or greater than85 Shore C, and most preferably about 88 Shore C or greater. In oneparticular embodiment, the surface hardness is greater than 82 Shore C.Alternatively, the outer core layer may have a surface hardness of about50 shore D or greater, more preferably about 55 Shore D or greater, andmost preferably about 60 Shore D or greater.

The core should also have a steep positive gradient from the outersurface of the outer core layer and preferably to the geometric centerof the core. In such case, the steep positive gradient is defined by theouter surface hardness of the outer core layer minus the center hardnessof the core geometric center as explained/defined more fully furtherbelow.

The core in a golf ball of the invention may for example have a Shore C(or JIS C) hardness gradient of at least about 20 hardness points, or atleast about 25 hardness points, or about 30 hardness points or greater,and may even be about 35 hardness points, or about 45 hardness points orgreater. Using the Shore D scale, the steep positive gradient may be,for example, about 15 Shore D or greater, about 20 shore D or greater,or about 25 Shore D or greater.

The thermoset rubber composition part/portion of the mixture may includefor example at least one base rubber such as a polybutadiene rubber,cured with at least one peroxide and at least one reactive co-agent(which can be a metal salt of an unsaturated carboxylic acid, such asacrylic acid or methacrylic acid, a non-metallic coagent, or mixturesthereof). An optional ‘soft and fast agent’ (and sometimes acis-to-trans catalyst) such as an organosulfur or metal-containingorganosulfur compound can also be included in the thermoset rubbercomposition formulation. To form the steep “positive hardness gradient”,a gradient-promoting additive is preferably added as detailed furtherbelow. Other ingredients that are known to those skilled in the art maybe used, and are understood to include, but not be limited to,density-adjusting fillers, process aides, plasticizers, blowing orfoaming agents, sulfur accelerators, and/or non-peroxide radicalsources.

The base thermoset rubber, which can be blended with other rubbers andpolymers, typically includes a natural or synthetic rubber. A preferredbase rubber is 1,4-polybutadiene having a cis structure of at least 40%,preferably greater than 80%, and more preferably greater than 90%.Non-limiting examples of suitable commercially available base rubbersare Buna CB high-cis neodymium-catalyzed polybutadiene rubbers, such asBuna CB 22, Buna CB 23, Buna CB24, and Buna CB high-cis cobalt-catalyzedpolybutadiene rubbers, such as Buna CB 1203, 1220 and 1221, commerciallyavailable from Lanxess Corporation; SE BR-1220, commercially availablefrom The Dow Chemical Company; Europrene® NEOCIS® BR 40 and BR 60,commercially available from Polimeri Europa®; UBEPOL® 360L and UBEPOL®150L and UBEPOL-BR® rubbers, commercially available from UBE Industries,Inc.; BR 01, BR 730, BR 735, BR 11 and BR 51, commercially availablefrom Japan Synthetic Rubber Co., Ltd.; Neodene high-cisneodymium-catalyzed polybutadiene rubbers, such as Neodene BR 40,commercially available from Karbochem; BUNA® CB Nd40 from Lanxess; andKARBOCHEM® ND40, ND45, and ND60, commercially available from Karbochem;TP-301 transpolyisoprene, commercially available from Kuraray Co., Ltd.;Vestenamer® polyoctenamer, commercially available from EvonikIndustries; Butyl 065 and Butyl 288 butyl rubbers, commerciallyavailable from ExxonMobil Chemical Company; Butyl 301 and Butyl 101-3,commercially available from Lanxess Corporation; Bromobutyl 2224 andChlorobutyl 1066 halobutyl rubbers, commercially available fromExxonMobil Chemical Company; Bromobutyl X2 and Chlorobutyl 1240halobutyl rubbers, commercially available from Lanxess Corporation;BromoButyl 2255 butyl rubber, commercially available from JapanSynthetic Rubber Co., Ltd.; Vistalon® 404 and Vistalon® 706 ethylenepropylene rubbers, commercially available from ExxonMobil ChemicalCompany; Dutral CO 058 ethylene propylene rubber, commercially availablefrom Polimeri Europa; Nordel® IP NDR 5565 and Nordel® IP 3670ethylene-propylene-diene rubbers, commercially available from The DowChemical Company; EPT1045 and EPT1045 ethylene-propylene-diene rubbers,commercially available from Mitsui Corporation; Buna SE 1721 TEstyrene-butadiene rubbers, commercially available from LanxessCorporation; Afpol 1500 and Afpol 552 styrene-butadiene rubbers,commercially available from Karbochem; Plioflex PLF 1502, commerciallyavailable from Goodyear Chemical; Nipol® DN407 and Nipol® 1041Lacrylonitrile butadiene rubbers, commercially available from ZeonChemicals, L.P.; Neoprene GRT and Neoprene AD30 polychloroprene rubbers;Vamac® ethylene acrylic elastomers, commercially available from E. I. duPont de Nemours and Company; Hytemp® AR12 and AR214 alkyl acrylaterubbers, commercially available from Zeon Chemicals, L.P.; Hypalon®chlorosulfonated polyethylene rubbers, commercially available from E. I.du Pont de Nemours and Company; and Goodyear Budene® 1207 polybutadiene,commercially available from Goodyear Chemical. In a particularembodiment, the core is formed from a rubber composition comprising asthe base rubber a blend of Neodene BR 40 polybutadiene, Budene® 1207polybutadiene, and Buna SB 1502 styrene butadiene rubber. In anotherparticular embodiment, the core is formed from a rubber compositioncomprising as the base rubber a blend of Neodene BR 40 polybutadiene,Buna CB 1221, and core regrind.

The base rubber may also comprise high or medium Mooney viscosityrubber, or blends thereof. The measurement of Mooney viscosity isdefined according to ASTM D-1646. The Mooney viscosity range ispreferably greater than about 40, more preferably in the range fromabout 40 to about 80 and more preferably in the range from about 40 toabout 60. Polybutadiene rubber with higher Mooney viscosity may also beused, so long as the viscosity of the polybutadiene does not reach alevel where the high viscosity polybutadiene clogs or otherwiseadversely interferes with the manufacturing machinery. It iscontemplated that polybutadiene with viscosity less than 65 Mooney canbe used with the present invention. In one embodiment of the presentinvention, golf ball core layers made with mid- to high-Mooney viscositypolybutadiene material exhibit increased resiliency (and, therefore,distance) without increasing the hardness of the ball.

Commercial sources of suitable mid- to high-Mooney viscositypolybutadiene include BUNA® CB23 (Nd-catalyzed), which has a Mooneyviscosity of around 50 and is a highly linear polybutadiene, and BUNA®CB 1220 (Co-catalyzed). If desired, the polybutadiene can also be mixedwith other elastomers known in the art, such as other polybutadienerubbers, natural rubber, styrene butadiene rubber, and/or isoprenerubber in order to further modify the properties of the core. When amixture of elastomers is used, the amounts of other constituents in thecore composition are typically based on 100 parts by weight of the totalelastomer mixture.

In one embodiment, the base rubber comprises a Nd-catalyzedpolybutadiene, a transition metal polybutadiene rubber, or blendsthereof. If desired, the polybutadiene can also be mixed with otherelastomers known in the art such as natural rubber, polyisoprene rubberand/or styrene-butadiene rubber in order to modify the properties of thecore. Other suitable base rubbers include thermosetting materials suchas, ethylene propylene diene monomer rubber, ethylene propylene rubber,butyl rubber, halobutyl rubber, hydrogenated nitrile butadiene rubber,nitrile rubber, and silicone rubber.

Suitable rubber compositions include a base rubber selected from naturaland synthetic rubbers, including, but not limited to, polybutadiene,polyisoprene, ethylene propylene rubber (“EPR”), ethylene propylenediene rubber (“EPDM”), styrene butadiene rubber, styrenic blockcopolymer rubber, butyl rubber, halobutyl rubber, copolymers ofisobutylene and para-alkylstyrene, halogenated copolymers of isobutyleneand para-alkylstyrene, acrylonitrile butadiene rubber, polychloroprene,alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrilechlorinated isoprene rubber, polystyrene elastomers, polyethyleneelastomers, polyurethane elastomers, polyurea elastomers,metallocene-catalyzed elastomers and plastomers, polyalkenamer, phenolformaldehyde, melamine formaldehyde, polyepoxide, polysiloxane, alkyd,polyisocyanurate, polycyanurate, polyacrylate, and combinations of twoor more thereof. Diene rubbers are preferred, particularlypolybutadiene, styrene butadiene, acrylonitrile butadiene, and mixturesof polybutadiene with other elastomers wherein the amount ofpolybutadiene present greater than 40 wt % based on the total polymericweight of the mixture.

The rubber is crosslinked using, for example, a peroxide or sulfur curesystem, C—C initiators, high energy radiation sources capable ofgenerating free radicals, or a combination thereof. The rubbercomposition optionally includes one or more of the following: scorchretarder, antioxidant, soft and fast agent, filler, processing aid,processing oil, coloring agent, fluorescent agent, chemical blowing andfoaming agent, defoaming agent, stabilizer, softening agent, impactmodifier, free radical scavenger, and antiozonant (e.g.,p-phenylenediames). Suitable types and amounts of rubber, initiatoragent, coagent, filler, and additives are more fully described in, forexample, U.S. Pat. Nos. 6,566,483, 6,695,718, 6,939,907, 7,041,721 and7,138,460, the entire disclosures of which are hereby incorporatedherein by reference. Particularly suitable diene rubber compositions arefurther disclosed, for example, in U.S. Pat. No. 7,654,918, the entiredisclosure of which is hereby incorporated herein by reference.

Additional thermoset polymers may also optionally be incorporated intothe base rubber, including for example, thermoset elastomers such ascore regrind.

Suitable peroxide initiating agents include dicumyl peroxide;2,5-dimethyl-2,5-di(t-butylperoxy) hexane;2,5-dimethyl-2,5-di(t-butylperoxy)hexyne;2,5-dimethyl-2,5-di(benzoylperoxy)hexane;2,2′-bis(t-butylperoxy)-di-iso-propylbenzene;1,1-bis(t-butylperoxy)-3,3,5-trimethyl cyclohexane; n-butyl4,4-bis(t-butyl-peroxy)valerate; t-butyl perbenzoate; benzoyl peroxide;n-butyl 4,4′-bis(butylperoxy) valerate; di-t-butyl peroxide; or2,5-di-(t-butylperoxy)-2,5-dimethyl hexane, lauryl peroxide, t-butylhydroperoxide, α-α bis(t-butylperoxy) diisopropylbenzene,di(2-t-butyl-peroxyisopropyl)benzene, di-t-amyl peroxide, di-t-butylperoxide. Preferably, the rubber composition includes from about 0.1 toabout 5.0 parts by weight peroxide per 100 parts by weight rubber (phr),or from about 0.25 phr to about 4.0 phr, or from about 0.5 phr to 3 phr,or from about 0.5 phr to about 1.5 phr. These ranges of peroxide aregiven assuming the peroxide is 100% active, without accounting for anycarrier that might be present. Because many commercially availableperoxides are sold along with a carrier compound, the actual amount ofactive peroxide present must be calculated. Commercially-availableperoxide initiating agents include DICUP™ family of dicumyl peroxides(including DICUP® R, DICUP® 40C and DICUP® 40KE) available from Crompton(Geo Specialty Chemicals). Similar initiating agents are available fromAkroChem, Lanxess, Flexsys/Harwick and R.T. Vanderbilt. Anothercommercially-available and preferred initiating agent is TRIGONOX®265-50B from Akzo Nobel, which is a mixture of1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane anddi(2-t-butylperoxyisopropyl) benzene. TRIGONOX® peroxides are generallysold on a carrier compound.

Suitable reactive co-agents include, but are not limited to, metal saltsof acrylic acid or methacrylic acid wherein the metal is zinc,magnesium, calcium, barium, tin, aluminum, lithium, sodium, potassium,iron, zirconium, and bismuth. Zinc diacrylate (ZDA) is preferred, butthe present invention is not limited thereto. ZDA provides golf ballswith a high initial velocity. The ZDA can be of various grades ofpurity. For the purposes of this invention, the lower the quantity ofzinc stearate present in the ZDA the higher the ZDA purity. ZDAcontaining less than about 10% zinc stearate is preferable. Morepreferable is ZDA containing about 4-8% zinc stearate. Suitable,commercially available zinc diacrylates include those from Total S.A.

In one embodiment of a golf ball of the invention incorporating a corecomprised of an inner core layer and the outer core layer, the innercore layer may for example comprise the coagent such as ZDA in an amountof from about 10 phr to about 30 parts by weight peroxide per 100 partsby weight rubber (phr), while the outer core layer comprises coagent inan amount of from about 25 phr to about 55 parts by weight peroxide per100 parts by weight rubber (phr).

The ZDA amount can be varied to suit the desired compression, spin andfeel of the resulting golf ball.

Additional preferred co-agents that may be used alone or in combinationwith those mentioned above include, but are not limited to,trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, andthe like. It is understood by those skilled in the art, that in the casewhere these co-agents may be liquids at room temperature, it may beadvantageous to disperse these compounds on a suitable carrier topromote ease of incorporation in the rubber mixture.

The cure regime can generally have a temperature range between fromabout 290° F. to about 390° F., more preferably about 320° F. to about375° F., and the stock is held at that temperature for at least about 10minutes to about 30 minutes.

To form the steep “positive” hardness gradient across the core, it ispreferred that a gradient-promoting additive is present. Suitable agentsinclude, but are not limited to benzoquinones, resorcinols, catechols,quinhydrones, and hydroquinones. Those, and other methods and materialfor creating a steep “positive” hardness gradient are disclosed in U.S.patent application Ser. Nos. 12/168,979; 12/168,987; 12/168,995; and12/169,002, which are incorporated herein by reference thereto.

The thermoset rubber composition of the present invention may alsoinclude an optional soft and fast agent. As used herein, “soft and fastagent” means any compound or a blend thereof that that is capable ofmaking a core 1) softer (lower compression) at constant COR or 2) have ahigher CoR at equal compression, or any combination thereof, whencompared to a core equivalently prepared without a soft and fast agent.Preferably, the composition of the present invention contains from about0.05 phr to about 10.0 phr soft and fast agent. In one embodiment, thesoft and fast agent is present in an amount of about 0.05 phr to about3.0 phr, preferably about 0.05 phr to about 2.0 phr, more preferablyabout 0.05 phr to about 1.0 phr. In another embodiment, the soft andfast agent is present in an amount of about 2.0 phr to about 5.0 phr,preferably about 2.35 phr to about 4.0 phr, and more preferably about2.35 phr to about 3.0 phr. In an alternative high concentrationembodiment, the soft and fast agent is present in an amount of about 5.0phr to about 10.0 phr, more preferably about 6.0 phr to about 9.0 phr,most preferably about 7.0 phr to about 8.0 phr. In a most preferredembodiment, the soft and fast agent is present in an amount of about 2.6phr.

Suitable soft and fast agents include, but are not limited to,organosulfur or metal-containing organosulfur compounds, an organicsulfur compound, including mono, di, and polysulfides, a thiol, ormercapto compound, an inorganic sulfide compound, a Group VIA compound,or mixtures thereof. The soft and fast agent component may also be ablend of an organosulfur compound and an inorganic sulfide compound.

Suitable soft and fast agents of the present invention include, but arenot limited to those having the following general formula:

where R₁-R₅ can be C₁-C₈ alkyl groups; halogen groups; thiol groups(—SH), carboxylated groups; sulfonated groups; and hydrogen; in anyorder; and also pentafluorothiophenol; 2-fluorothiophenol;3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol;2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentachlorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol;4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol;3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol;3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol;2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol;3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; and their zinc salts. Preferably, thehalogenated thiophenol compound is pentachlorothiophenol, which iscommercially available in neat form or under the tradename STRUKTOL®, aclay-based carrier containing the sulfur compound pentachlorothiophenolloaded at 45 percent (correlating to 2.4 parts PCTP). STRUKTOL® iscommercially available from Struktol Company of America of Stow, Ohio.PCTP is commercially available in neat form from eChinachem of SanFrancisco, Calif. and in the salt form, also from eChinachem. Mostpreferably, the halogenated thiophenol compound is the zinc salt ofpentachlorothiophenol, which is commercially available from eChinachem.

As used herein when referring to the invention, the term “organosulfurcompound(s)” refers to any compound containing carbon, hydrogen, andsulfur, where the sulfur is directly bonded to at least 1 carbon. Asused herein, the term “sulfur compound” means a compound that iselemental sulfur, polymeric sulfur, or a combination thereof. It shouldbe further understood that the term “elemental sulfur” refers to thering structure of S₈ and that “polymeric sulfur” is a structureincluding at least one additional sulfur relative to elemental sulfur.

Additional suitable examples of soft and fast agents (that are alsobelieved to be cis-to-trans catalysts) include, but are not limited to,4,4′-diphenyl disulfide; 4,4′-ditolyl disulfide; 2,2′-benzamido diphenyldisulfide; bis(2-aminophenyl) disulfide; bis(4-aminophenyl) disulfide;bis(3-aminophenyl) disulfide; 2,2′-bis(4-aminonaphthyl) disulfide;2,2′-bis(3-aminonaphthyl) disulfide; 2,2′-bis(4-aminonaphthyl)disulfide; 2,2′-bis(5-aminonaphthyl) disulfide;2,2′-bis(6-aminonaphthyl) disulfide; 2,2′-bis(7-aminonaphthyl)disulfide; 2,2′-bis(8-aminonaphthyl) disulfide;1,1′-bis(2-aminonaphthyl) disulfide; 1,1′-bis(3-aminonaphthyl)disulfide; 1,1′-bis(3-aminonaphthyl) disulfide;1,1′-bis(4-aminonaphthyl) disulfide; 1,1′-bis(5-aminonaphthyl)disulfide; 1,1′-bis(6-aminonaphthyl) disulfide;1,1′-bis(7-aminonaphthyl) disulfide; 1,1′-bis(8-aminonaphthyl)disulfide; 1,2′-diamino-1,2′-dithiodinaphthalene;2,3′-diamino-1,2′-dithiodinaphthalene; bis(4-chlorophenyl) disulfide;bis(2-chlorophenyl) disulfide; bis(3-chlorophenyl) disulfide;bis(4-bromophenyl) disulfide; bis(2-bromophenyl) disulfide;bis(3-bromophenyl) disulfide; bis(4-fluorophenyl) disulfide;bis(4-iodophenyl) disulfide; bis(2,5-dichlorophenyl) disulfide;bis(3,5-dichlorophenyl) disulfide; bis (2,4-dichlorophenyl) disulfide;bis(2,6-dichlorophenyl) disulfide; bis(2,5-dibromophenyl) disulfide;bis(3,5-dibromophenyl) disulfide; bis(2-chloro-5-bromophenyl) disulfide;bis(2,4,6-trichlorophenyl) disulfide; bis(2,3,4,5,6-pentachlorophenyl)disulfide; bis(4-cyanophenyl) disulfide; bis(2-cyanophenyl) disulfide;bis(4-nitrophenyl) disulfide; bis(2-nitrophenyl) disulfide;2,2′-dithiobenzoic acid ethylester; 2,2′-dithiobenzoic acid methylester;2,2′-dithiobenzoic acid; 4,4′-dithiobenzoic acid ethylester;bis(4-acetylphenyl) disulfide; bis(2-acetylphenyl) disulfide;bis(4-formylphenyl) disulfide; bis(4-carbamoylphenyl) disulfide;1,1′-dinaphthyl disulfide; 2,2′-dinaphthyl disulfide; 1,2′-dinaphthyldisulfide; 2,2′-bis(1-chlorodinaphthyl) disulfide;2,2′-bis(1-bromonaphthyl) disulfide; 1,1′-bis(2-chloronaphthyl)disulfide; 2,2′-bis(1-cyanonaphthyl) disulfide;2,2′-bis(1-acetylnaphthyl) disulfide; and the like; or a mixturethereof. Preferred organosulfur components include 4,4′-diphenyldisulfide, 4,4′-ditolyl disulfide, or 2,2′-benzamido diphenyl disulfide,or a mixture thereof. A more preferred organosulfur component includes4,4′-ditolyl disulfide. In another embodiment, metal-containingorganosulfur components can be used according to the invention. Suitablemetal-containing organosulfur components include, but are not limitedto, cadmium, copper, lead, and tellurium analogs ofdiethyldithiocarbamate, diamyldithiocarbamate, anddimethyldithiocarbamate, or mixtures thereof.

Suitable substituted or unsubstituted aromatic organic components thatdo not include sulfur or a metal include, but are not limited to,4,4′-diphenyl acetylene, azobenzene, or a mixture thereof. The aromaticorganic group preferably ranges in size from C₆ to C₂₀, and morepreferably from C₆ to C₁₀. Suitable inorganic sulfide componentsinclude, but are not limited to titanium sulfide, manganese sulfide, andsulfide analogs of iron, calcium, cobalt, molybdenum, tungsten, copper,selenium, yttrium, zinc, tin, and bismuth.

A substituted or unsubstituted aromatic organic compound is alsosuitable as a soft and fast agent. Suitable substituted or unsubstitutedaromatic organic components include, but are not limited to, componentshaving the formula (R₁)_(c)—R₃-M-R₄—(R₂)_(y), wherein R₁ and R₂ are eachhydrogen or a substituted or unsubstituted C₁₋₂₀ linear, branched, orcyclic alkyl, alkoxy, or alkylthio group, or a single, multiple, orfused ring C₆ to C₂₄ aromatic group; x and y are each an integer from 0to 5; R₃ and R₄ are each selected from a single, multiple, or fused ringC₆ to C₂₄ aromatic group; and M includes an azo group or a metalcomponent. R₃ and R₄ are each preferably selected from a C₆ to C₁₀aromatic group, more preferably selected from phenyl, benzyl, naphthyl,benzamido, and benzothiazyl. R₁ and R₂ are each preferably selected froma substituted or unsubstituted C₁ to C₁₀ linear, branched, or cyclicalkyl, alkoxy, or alkylthio group or a C₆ to C₁₀ aromatic group. WhenR₁, R₂, R₃, or R₄, are substituted, the substitution may include one ormore of the following substituent groups: hydroxy and metal saltsthereof; mercapto and metal salts thereof; halogen; amino, nitro, cyano,and amido; carboxyl including esters, acids, and metal salts thereof;silyl; acrylates and metal salts thereof; sulfonyl or sulfonamide; andphosphates and phosphites. When M is a metal component, it may be anysuitable elemental metal available to those of ordinary skill in theart. Typically, the metal will be a transition metal, althoughpreferably it is tellurium or selenium. In one embodiment, the aromaticorganic compound is substantially free of metal, while in anotherembodiment the aromatic organic compound is completely free of metal.

The soft and fast agent can also include a Group VIA component.Elemental sulfur and polymeric sulfur are commercially available fromElastochem, Inc. of Chardon, Ohio Exemplary sulfur catalyst compoundsinclude PB(RM-S)-80 elemental sulfur and PB(CRST)-65 polymeric sulfur,each of which is available from Elastochem, Inc. An exemplary telluriumcatalyst under the tradename TELLOY® and an exemplary selenium catalystunder the tradename VANDEX® are each commercially available from RTVanderbilt.

Other suitable soft and fast agents include, but are not limited to,hydroquinones, benzoquinones, quinhydrones, catechols, and resorcinols.Suitable compounds include, but are not limited to, those disclosed inU.S. patent application Ser. No. 11/829,461, the disclosure of which isincorporated herein in its entirety by reference thereto.

Fillers may also be added to the thermoset rubber composition of thecore to adjust the density of the composition, up or down. Typically,fillers include materials such as tungsten, zinc oxide, barium sulfate,silica, calcium carbonate, zinc carbonate, metals, metal oxides andsalts, regrind (recycled core material typically ground to about 30 meshparticle), high-Mooney-viscosity rubber regrind, trans-regrind corematerial (recycled core material containing high trans-isomer ofpolybutadiene), and the like. When trans-regrind is present, the amountof trans-isomer is preferably between about 10% and about 60%. In apreferred embodiment of the invention, the core comprises polybutadienehaving a cis-isomer content of greater than about 95% and trans-regrindcore material (already vulcanized) as a filler. Any particle sizetrans-regrind core material is sufficient, but is preferably less thanabout 125 μm.

Fillers added to one or more portions of the golf ball typically includeprocessing aids or compounds to affect rheological and mixingproperties, density-modifying fillers, tear strength, or reinforcementfillers, and the like. The fillers are generally inorganic, and suitablefillers include numerous metals or metal oxides, such as zinc oxide andtin oxide, as well as barium sulfate, zinc sulfate, calcium carbonate,barium carbonate, clay, tungsten, tungsten carbide, an array of silicas,and mixtures thereof. Fillers may also include various foaming agents orblowing agents which may be readily selected by one of ordinary skill inthe art. Fillers may include polymeric, ceramic, metal, and glassmicrospheres may be solid or hollow, and filled or unfilled. Fillers aretypically also added to one or more portions of the golf ball to modifythe density thereof to conform to uniform golf ball standards. Fillersmay also be used to modify the weight of the center or at least oneadditional layer for specialty balls, e.g., a lower weight ball ispreferred for a player having a low swing speed.

Materials such as tungsten, zinc oxide, barium sulfate, silica, calciumcarbonate, zinc carbonate, metals, metal oxides and salts, and regrind(recycled core material typically ground to about 30 mesh particle) arealso suitable fillers.

The polybutadiene and/or any other base rubber or elastomer system mayalso be foamed, or filled with hollow microspheres or with expandablemicrospheres which expand at a set temperature during the curing processto any low specific gravity level. Other ingredients such as sulfuraccelerators, e.g., tetra methylthiuram di, tri, or tetrasulfide, and/ormetal-containing organosulfur components may also be used according tothe invention. Suitable metal-containing organosulfur acceleratorsinclude, but are not limited to, cadmium, copper, lead, and telluriumanalogs of diethyldithiocarbamate, diamyldithiocarbamate, anddimethyldithiocarbamate, or mixtures thereof. Other ingredients such asprocessing aids e.g., fatty acids and/or their metal salts, processingoils, dyes and pigments, as well as other additives known to one skilledin the art may also be used in the present invention in amountssufficient to achieve the purpose for which they are typically used.

Core or core layers comprising synthetic flocks, preferably polyester ornylon flocks, include a base rubber such as a polybutadiene or a blendof polybutadienes, zinc oxide, reactive coagents such as ZDA, ZDMA, HVA,SR-350, SR-351 or other coagents sold by Cray Valley company, a peroxideor blends of peroxides, a soft and fast agent such as Zn PCTP, or PCTP,fatty acids/salts thereof, fillers such as calcium carbonate or bariumsulfate, antioxidants, and antiozonants. The polybutadiene may beblended with other rubbers such as polyoctenamer, natural rubber, EPDM,cis-polyisoprene, trans-polyisoprene, SBR and other diene rubbers toname a few.

The preferred level of flock blended into the uncured stock is 0.5 to 15phr, more preferably 1 to 10 phr and the preferred flock is nylon orpolyester. A preferred rubber composition for the outer core is 100 phrby weight of a base rubber such as CB 23, 20 to 50 phr of a cogent, 5 to50 phr of zinc oxide, 10 to 60 phr of an inorganic filler, 0.1 to 5 phran organic peroxide, 0.05 phr to 3 phr of an organosulfur, 1 to 10 phrof a nylon flock. The fiber should be blended together with the othercomponents at a temperature below the melting point of the fiber topreserve fibrous shape. Blends of fibers, including blends of differentmaterials and sizes and can be used in combination with other types ofreinforcing fillers. Preferred fibers are polymeric types with meltingpoints greater than mixing temperature used to pre-blend theingredients. Commercially available examples of suitable flocks includethose sold by Akrochem Corp. as Akroflocks, such as nylon, polyester,polypropylene, aramid, or acrylic flocks.

A preferred outer core layer containing the flock should have 25-45 phrof a crosslinking coagent (ZDA for example) and the center should haveabout 10 to 30 phr of coagent.

It is envisioned that a golf ball of the invention incorporating theflock-containing core layer may otherwise have any known construction(e.g., inner core layer, intermediate core layer, inner cover layer,outer cover layer, etc.), and that each other layer may comprise anyknown golf ball material such as ionomers, polyurethanes, polyureas,TPE, HNP, crosslinked rubber, etc., or blends/mixtures/combinationsthereof.

In this regard, where one or more of these other layers comprises arubber composition, suitable base rubbers may include for example thoseidentified above in connection with the flock-containing core layer. Andsuitable thermoplastic materials for these other golf ball layersinclude for example ionomers (more specifically HNP type ionomers asdescribed for example in U.S. Pat. No. 7,867,106) and non-ionomericmaterials such as polyether-esters and polyester-amides, or blendsthereof. Additional suitable compositions for these other layers aredisclosed, for example, in U.S. Pat. Nos. 6,953,820 and 6,939,907, andU.S. Pat. Nos. 5,919,100, 6,653,382, 6,872,774, 7,074,137, and7,300,364, the entire disclosures of which are hereby incorporatedherein by reference.

Suitable ionomer compositions for these other layers include partiallyneutralized ionomers and highly neutralized ionomers, including ionomersformed from blends of two or more partially neutralized ionomers, blendsof two or more highly neutralized ionomers, and blends of one or morepartially neutralized ionomers with one or more highly neutralizedionomers. Preferred ionomers are salts of O/X- and O/X/Y-type acidcopolymers, wherein O is an α-olefin, X is a C₃-C₈ α,β-ethylenicallyunsaturated carboxylic acid, and Y is a softening monomer. O ispreferably selected from ethylene and propylene. X is preferablyselected from methacrylic acid, acrylic acid, ethacrylic acid, crotonicacid, and itaconic acid. Methacrylic acid and acrylic acid areparticularly preferred. As used herein, “(meth) acrylic acid” meansmethacrylic acid and/or acrylic acid. Likewise, “(meth) acrylate” meansmethacrylate and/or acrylate. Y is preferably selected from (meth)acrylate and alkyl (meth) acrylates wherein the alkyl groups have from 1to 8 carbon atoms, including, but not limited to, n-butyl (meth)acrylate, isobutyl (meth) acrylate, methyl (meth) acrylate, and ethyl(meth) acrylate. Particularly preferred O/X/Y-type copolymers areethylene/(meth) acrylic acid/n-butyl (meth) acrylate, ethylene/(meth)acrylic acid/isobutyl (meth) acrylate, ethylene/(meth) acrylicacid/methyl (meth) acrylate, and ethylene/(meth) acrylic acid/ethyl(meth) acrylate. The acid is typically present in the acid copolymer inan amount of 6 wt % or greater, or 9 wt % or greater, or 10 wt % orgreater, or 11 wt % or greater, or 15 wt % or greater, or 16 wt % orgreater, or 19 wt % or greater, or 20 wt % or greater, or in an amountwithin a range having a lower limit of 1 or 4 or 6 or 8 or 10 or 11 or12 or 15 wt % and an upper limit of 15 or 16 or 17 or 19 or 20 or 20.5or 21 or 25 or 30 or 35 or 40 wt %, based on the total weight of theacid copolymer. The acid copolymer is at least partially neutralizedwith a cation source, optionally in the presence of a high molecularweight organic acid, such as those disclosed in U.S. Pat. No. 6,756,436,the entire disclosure of which is hereby incorporated herein byreference. In a particular embodiment, less than 40% of the acid groupspresent in the composition are neutralized. In another particularembodiment, from 40% to 60% of the acid groups present in thecomposition are neutralized. In another particular embodiment, from 60%to 70% of the acid groups present in the composition are neutralized. Inanother particular embodiment, from 60% to 80% of the acid groupspresent in the composition are neutralized. In another particularembodiment, from 70% to 80% of the acid groups present in thecomposition are neutralized. In another embodiment, from 80% to 100% ofthe acid groups present in the composition are neutralized. Suitablecation sources include, but are not limited to, metal ion sources, suchas compounds of alkali metals, alkaline earth metals, transition metals,and rare earth elements; ammonium salts and monoamine salts; andcombinations thereof. Preferred cation sources are compounds ofmagnesium, sodium, potassium, cesium, calcium, barium, manganese,copper, zinc, tin, lithium, and rare earth metals. In a particularembodiment, the ionomer composition includes a bimodal ionomer, forexample, DuPont® AD1043 ionomers, and the ionomers disclosed in U.S.Pat. No. 7,037,967 and U.S. Pat. Nos. 6,562,906, 6,762,246 and7,273,903, the entire disclosures of which are hereby incorporatedherein by reference. Suitable ionomers are further disclosed, forexample, in U.S. Pat. Nos. 5,587,430, 5,691,418, 5,866,658, 6,100,321,6,653,382, 6,756,436, 6,777,472, 6,815,480, 6,894,098, 6,919,393,6,953,820, 6,994,638, 7,230,045, 7,375,151, 7,429,624, and 7,652,086,the entire disclosures of which are hereby incorporated herein byreference.

Suitable ionomer compositions also include blends of one or morepartially- or fully-neutralized polymers with additional thermoplasticand thermoset materials, including, but not limited to, non-ionomericacid copolymers, engineering thermoplastics, fatty acid/salt-basedhighly neutralized polymers, polybutadienes, polyurethanes, polyureas,polyesters, polyamides, polycarbonate/polyester blends, thermoplasticelastomers, maleic anhydride-grafted metallocene-catalyzed polymers(e.g., maleic anhydride-grafted metallocene-catalyzed polyethylene), andother conventional polymeric materials.

Suitable ionomeric compositions are further disclosed, for example, inU.S. Pat. Nos. 6,653,382, 6,756,436, 6,777,472, 6,894,098, 6,919,393,and 6,953,820, the entire disclosures of which are hereby incorporatedherein by reference.

Also suitable are polyester ionomers, including, but not limited to,those disclosed, for example, in U.S. Pat. Nos. 6,476,157 and 7,074,465,the entire disclosures of which are hereby incorporated herein byreference.

Also suitable are thermoplastic elastomers comprising a siliconeionomer, as disclosed, for example, in U.S. Pat. No. 8,329,156, theentire disclosure of which is hereby incorporated herein by reference.

Also suitable are the following non-ionomeric polymers, includinghomopolymers and copolymers thereof, as well as their derivatives thatare compatibilized with at least one grafted or copolymerized functionalgroup, such as maleic anhydride, amine, epoxy, isocyanate, hydroxyl,sulfonate, phosphonate, and the like:

(a) polyesters, particularly those modified with a compatibilizing groupsuch as sulfonate or phosphonate, including modified poly(ethyleneterephthalate), modified poly(butylene terephthalate), modifiedpoly(propylene terephthalate), modified poly(trimethyleneterephthalate), modified poly(ethylene naphthenate), and those disclosedin U.S. Pat. Nos. 6,353,050, 6,274,298, and 6,001,930, the entiredisclosures of which are hereby incorporated herein by reference, andblends of two or more thereof;(b) polyamides, polyamide-ethers, and polyamide-esters, and thosedisclosed in U.S. Pat. Nos. 6,187,864, 6,001,930, and 5,981,654, theentire disclosures of which are hereby incorporated herein by reference,and blends of two or more thereof;(c) polyurethanes, polyureas, polyurethane-polyurea hybrids, and blendsof two or more thereof;(d) fluoropolymers, such as those disclosed in U.S. Pat. Nos. 5,691,066,6,747,110 and 7,009,002, the entire disclosures of which are herebyincorporated herein by reference, and blends of two or more thereof;(e) non-ionomeric acid polymers, such as E/X- and E/X/Y-type copolymers,wherein E is an olefin (e.g., ethylene), X is a carboxylic acid such asacrylic, methacrylic, crotonic, maleic, fumaric, or itaconic acid, and Yis an optional softening comonomer such as vinyl esters of aliphaticcarboxylic acids wherein the acid has from 2 to 10 carbons, alkyl etherswherein the alkyl group has from 1 to 10 carbons, and alkylalkylacrylates such as alkyl methacrylates wherein the alkyl group hasfrom 1 to 10 carbons; and blends of two or more thereof;(f) metallocene-catalyzed polymers, such as those disclosed in U.S. Pat.Nos. 6,274,669, 5,919,862, 5,981,654, and 5,703,166, the entiredisclosures of which are hereby incorporated herein by reference, andblends of two or more thereof;(g) polystyrenes, such as poly(styrene-co-maleic anhydride),acrylonitrile-butadiene-styrene, poly(styrene sulfonate), polyethylenestyrene, and blends of two or more thereof;(h) polypropylenes and polyethylenes, particularly grafted polypropyleneand grafted polyethylenes that are modified with a functional group,such as maleic anhydride of sulfonate, and blends of two or morethereof;(i) polyvinyl chlorides and grafted polyvinyl chlorides, and blends oftwo or more thereof;(j) polyvinyl acetates, preferably having less than about 9% of vinylacetate by weight, and blends of two or more thereof;(k) polycarbonates, blends ofpolycarbonate/acrylonitrile-butadiene-styrene, blends ofpolycarbonate/polyurethane, blends of polycarbonate/polyester, andblends of two or more thereof;(l) polyvinyl alcohols, and blends of two or more thereof;(m) polyethers, such as polyarylene ethers, polyphenylene oxides, blockcopolymers of alkenyl aromatics with vinyl aromatics and poly(amicester)s, and blends of two or more thereof;(n) polyimides, polyetherketones, polyamideimides, and blends of two ormore thereof;(o) polycarbonate/polyester copolymers and blends; and(p) combinations of any two or more of the above thermoplastic polymers.

In general, polyurea compositions contain urea linkages formed byreacting an isocyanate group (—N═C═O) with an amine group (NH or NH₂).The chain length of the polyurea prepolymer is extended by reacting theprepolymer with an amine curing agent. The resulting polyurea haselastomeric properties, because of its “hard” and “soft” segments, whichare covalently bonded together. The soft, amorphous, low-melting pointsegments, which are formed from the polyamines, are relatively flexibleand mobile, while the hard, high-melting point segments, which areformed from the isocyanate and chain extenders, are relatively stiff andimmobile. The phase separation of the hard and soft segments providesthe polyurea with its elastomeric resiliency. The polyurea compositioncontains urea linkages having the following general structure:

where x is the chain length, i.e., about 1 or greater, and R and R₁ arestraight chain or branched hydrocarbon chains having about 1 to about 20carbon atoms.

Meanwhile, a polyurea/polyurethane hybrid composition is produced whenthe polyurea prepolymer (as described above) is chain-extended using ahydroxyl-terminated curing agent. Any excess isocyanate groups in theprepolymer will react with the hydroxyl groups in the curing agent andcreate urethane linkages. That is, a polyurea/polyurethane hybridcomposition is produced.

In a preferred embodiment, a pure polyurea composition, as describedabove, is prepared. That is, the composition contains only urealinkages. An amine-terminated curing agent is used in the reaction toproduce the pure polyurea composition. However, it should be understoodthat a polyurea/polyurethane hybrid composition also may be prepared inaccordance with this invention as discussed above. Such a hybridcomposition can be formed if the polyurea prepolymer is cured with ahydroxyl-terminated curing agent. Any excess isocyanate in the polyureaprepolymer reacts with the hydroxyl groups in the curing agent and formsurethane linkages. The resulting polyurea/polyurethane hybridcomposition contains both urea and urethane linkages. The generalstructure of a urethane linkage is shown below:

where x is the chain length, i.e., about 1 or greater, and R and R₁ arestraight chain or branched hydrocarbon chains having about 1 to about 20carbon atoms.

Two techniques for making the polyurea and polyurea/urethanecompositions include: a) one-shot technique, and b) prepolymertechnique. In the one-shot technique, the isocyanate blend, polyamine,and hydroxyl and/or amine-terminated curing agent are reacted in onestep. On the other hand, the prepolymer technique involves a firstreaction between the isocyanate blend and polyamine to produce apolyurea prepolymer, and a subsequent reaction between the prepolymerand hydroxyl and/or amine-terminated curing agent. As a result of thereaction between the isocyanate and polyamine compounds, there will besome unreacted NCO groups in the polyurea prepolymer. The prepolymershould have less than 14% unreacted NCO groups. Preferably, theprepolymer has no greater than 8.5% unreacted NCO groups, morepreferably from 2.5% to 8%, and most preferably from 5.0% to 8.0%unreacted NCO groups. As the weight percent of unreacted isocyanategroups increases, the hardness of the composition also generallyincreases.

Either the one-shot or prepolymer method may be employed to produce thepolyurea and polyurea/urethane compositions; however, the prepolymertechnique is preferred because it provides better control of thechemical reaction. The prepolymer method provides a more homogeneousmixture resulting in a more consistent polymer composition. The one-shotmethod results in a mixture that is inhomogeneous (more random) andaffords the manufacturer less control over the molecular structure ofthe resultant composition.

In the casting process, the polyurea and polyurea/urethane compositionscan be formed by chain-extending the polyurea prepolymer with a singlecuring agent or blend of curing agents as described further below. Thecompositions of the present invention may be selected from among bothcastable thermoplastic and thermoset materials. Thermoplastic polyureacompositions are typically formed by reacting the isocyanate blend andpolyamines at a 1:1 stoichiometric ratio. Thermoset compositions, on theother hand, are cross-linked polymers and are typically produced fromthe reaction of the isocyanate blend and polyamines at normally a 1.05:1stoichiometric ratio. In general, thermoset polyurea compositions areeasier to prepare than thermoplastic polyureas.

The polyurea prepolymer can be chain-extended by reacting it with asingle curing agent or blend of curing agents (chain-extenders). Ingeneral, the prepolymer can be reacted with hydroxyl-terminated curingagents, amine-terminated curing agents, or mixtures thereof. The curingagents extend the chain length of the prepolymer and build-up itsmolecular weight. Normally, the prepolymer and curing agent are mixed sothe isocyanate groups and hydroxyl or amine groups are mixed at a1.05:1.00 stoichiometric ratio.

A catalyst may be employed to promote the reaction between theisocyanate and polyamine compounds for producing the prepolymer orbetween prepolymer and curing agent during the chain-extending step.Preferably, the catalyst is added to the reactants before producing theprepolymer. Suitable catalysts include, but are not limited to, bismuthcatalyst; zinc octoate; stannous octoate; tin catalysts such asbis-butyltin dilaurate, bis-butyltin diacetate, stannous octoate; tin(II) chloride, tin (IV) chloride, bis-butyltin dimethoxide,dimethyl-bis[1-oxonedecyl)oxy]stannane, di-n-octyltin bis-isooctylmercaptoacetate; amine catalysts such as triethylenediamine,triethylamine, and tributylamine; organic acids such as oleic acid andacetic acid; delayed catalysts; and mixtures thereof. The catalyst ispreferably added in an amount sufficient to catalyze the reaction of thecomponents in the reactive mixture. In one embodiment, the catalyst ispresent in an amount from about 0.001 percent to about 1 percent, andpreferably 0.1 to 0.5 percent, by weight of the composition.

The hydroxyl chain-extending (curing) agents are preferably selectedfrom the group consisting of ethylene glycol; diethylene glycol;polyethylene glycol; propylene glycol; 2-methyl-1,3-propanediol;2-methyl-1,4-butanediol; monoethanolamine; diethanolamine;triethanolamine; monoisopropanolamine; diisopropanolamine; dipropyleneglycol; polypropylene glycol; 1,2-butanediol; 1,3-butanediol;1,4-butanediol; 2,3-butanediol; 2,3-dimethyl-2,3-butanediol;trimethylolpropane; cyclohexyldimethylol; triisopropanolamine;N,N,N′,N′-tetra-(2-hydroxypropyl)-ethylene diamine; diethylene glycolbis-(aminopropyl) ether; 1,5-pentanediol; 1,6-hexanediol;1,3-bis-(2-hydroxyethoxy) cyclohexane; 1,4-cyclohexyldimethylol;1,3-bis-[2-(2-hydroxyethoxy) ethoxy]cyclohexane;1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy}cyclohexane;trimethylolpropane; polytetramethylene ether glycol (PTMEG), preferablyhaving a molecular weight from about 250 to about 3900; and mixturesthereof.

Suitable amine chain-extending (curing) agents that can be used inchain-extending the polyurea prepolymer of this invention include, butare not limited to, unsaturated diamines such as4,4′-diamino-diphenylmethane (i.e., 4,4′-methylene-dianiline or “MDA”),m-phenylenediamine, p-phenylenediamine, 1,2- or1,4-bis(sec-butylamino)benzene, 3,5-diethyl-(2,4- or 2,6-)toluenediamine or “DETDA”, 3,5-dimethylthio-(2,4- or2,6-)toluenediamine, 3,5-diethylthio-(2,4- or 2,6-)toluenediamine,3,3′-dimethyl-4,4′-diamino-diphenylmethane,3,3′-diethyl-5,5′-dimethyl4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2-ethyl-6-methyl-benezeneamine)),3,3′-dichloro-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2-chloroaniline) or “MOCA”),3,3′,5,5′-tetraethyl-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2,6-diethylaniline),2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(3-chloro-2,6-diethyleneaniline) or “MCDEA”),3,3′-diethyl-5,5′-dichloro-4,4′-diamino-diphenylmethane, or “MDEA”),3,3′-dichloro-2,2′,6,6′-tetraethyl-4,4′-diamino-diphenylmethane,3,3′-dichloro-4,4′-diamino-diphenylmethane,4,4′-methylene-bis(2,3-dichloroaniline) (i.e.,2,2′,3,3′-tetrachloro-4,4′-diamino-diphenylmethane or “MDCA”),4,4′-bis(sec-butylamino)-diphenylmethane,N,N′-dialkylamino-diphenylmethane,trimethyleneglycol-di(p-aminobenzoate),polyethyleneglycol-di(p-aminobenzoate),polytetramethyleneglycol-di(p-aminobenzoate); saturated diamines such asethylene diamine, 1,3-propylene diamine, 2-methyl-pentamethylenediamine, hexamethylene diamine, 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine, imino-bis(propylamine), imido-bis(propylamine),methylimino-bis(propylamine) (i.e.,N-(3-aminopropyl)-N-methyl-1,3-propanediamine),1,4-bis(3-aminopropoxy)butane (i.e.,3,3′-[1,4-butanediylbis-(oxy)bis]-1-propanamine),diethyleneglycol-bis(propylamine) (i.e.,diethyleneglycol-di(aminopropyl)ether),4,7,10-trioxatridecane-1,13-diamine, 1-methyl-2,6-diamino-cyclohexane,1,4-diamino-cyclohexane, poly(oxyethylene-oxypropylene) diamines, 1,3-or 1,4-bis(methylamino)-cyclohexane, isophorone diamine, 1,2- or1,4-bis(sec-butylamino)-cyclohexane, N,N′-diisopropyl-isophoronediamine, 4,4′-diamino-dicyclohexylmethane,3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane,3,3′-dichloro-4,4′-diamino-dicyclohexylmethane,N,N′-dialkylamino-dicyclohexylmethane, polyoxyethylene diamines,3,3′-diethyl-5,5′-dimethyl-4,4′-diamino-dicyclohexylmethane,polyoxypropylene diamines,3,3′-diethyl-5,5′-dichloro-4,4′-diamino-dicyclohexylmethane,polytetramethylene ether diamines, 3,3′,5,5‘-tetraethyl-4,4’-diamino-dicyclohexylmethane (i.e.,4,4′-methylene-bis(2,6-diethylaminocyclohexane)),3,3′-dichloro-4,4′-diamino-dicyclohexylmethane,2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′-diamino-dicyclohexylmethane,(ethylene oxide)-capped polyoxypropylene ether diamines,2,2′,3,3′-tetrachloro-4,4′-diamino-dicyclohexylmethane,4,4′-bis(sec-butylamino)-dicyclohexylmethane; triamines such asdiethylene triamine, dipropylene triamine, (propylene oxide)-basedtriamines (i.e., polyoxypropylene triamines),N-(2-aminoethyl)-1,3-propylenediamine (i.e., N₃-amine), glycerin-basedtriamines, (all saturated); tetramines such asN,N′-bis(3-aminopropyl)ethylene diamine (i.e., N₄-amine) (bothsaturated), triethylene tetramine; and other polyamines such astetraethylene pentamine (also saturated). One suitable amine-terminatedchain-extending agent is Ethacure 300™ (dimethylthiotoluenediamine or amixture of 2,6-diamino-3,5-dimethylthiotoluene and2,4-diamino-3,5-dimethylthiotoluene.) The amine curing agents used aschain extenders normally have a cyclic structure and a low molecularweight (250 or less).

When the polyurea prepolymer is reacted with amine-terminated curingagents during the chain-extending step, as described above, theresulting composition is essentially a pure polyurea composition. On theother hand, when the polyurea prepolymer is reacted with ahydroxyl-terminated curing agent during the chain-extending step, anyexcess isocyanate groups in the prepolymer will react with the hydroxylgroups in the curing agent and create urethane linkages to form apolyurea/urethane hybrid.

This chain-extending step, which occurs when the polyurea prepolymer isreacted with hydroxyl curing agents, amine curing agents, or mixturesthereof, builds-up the molecular weight and extends the chain length ofthe prepolymer. When the polyurea prepolymer is reacted with aminecuring agents, a polyurea composition having urea linkages is produced.When the polyurea prepolymer is reacted with hydroxyl curing agents, apolyurea/urethane hybrid composition containing both urea and urethanelinkages is produced. The polyurea/urethane hybrid composition isdistinct from the pure polyurea composition. The concentration of ureaand urethane linkages in the hybrid composition may vary. In general,the hybrid composition may contain a mixture of about 10 to 90% urea andabout 90 to 10% urethane linkages. The resulting polyurea orpolyurea/urethane hybrid composition has elastomeric properties based onphase separation of the soft and hard segments. The soft segments, whichare formed from the polyamine reactants, are generally flexible andmobile, while the hard segments, which are formed from the isocyanatesand chain extenders, are generally stiff and immobile.

In an alternative embodiment, at least one layer may be formed from apolyurethane or polyurethane/urea hybrid composition. As discussedabove, in general, polyurethane compositions contain urethane linkagesformed by reacting an isocyanate group (—N═C═O) with a hydroxyl group(OH). The polyurethanes are produced by the reaction of amulti-functional isocyanate (NCO—R—NCO) with a long-chain polyol havingterminal hydroxyl groups (OH—OH) in the presence of a catalyst and otheradditives. The chain length of the polyurethane prepolymer is extendedby reacting it with short-chain diols (OH—R′—OH). The resultingpolyurethane has elastomeric properties because of its “hard” and “soft”segments, which are covalently bonded together. This phase separationoccurs because the mainly non-polar, low melting soft segments areincompatible with the polar, high melting hard segments. The hardsegments, which are formed by the reaction of the diisocyanate and lowmolecular weight chain-extending diol, are relatively stiff andimmobile. The soft segments, which are formed by the reaction of thediisocyanate and long chain diol, are relatively flexible and mobile.Because the hard segments are covalently coupled to the soft segments,they inhibit plastic flow of the polymer chains, thus creatingelastomeric resiliency.

Suitable isocyanate compounds that can be used to prepare thepolyurethane or polyurethane/urea hybrid material are described above.These isocyanate compounds are able to react with the hydroxyl or aminecompounds and form a durable and tough polymer having a high meltingpoint. The resulting polyurethane generally has good mechanical strengthand cut/shear-resistance. In addition, the polyurethane composition hasgood light and thermal-stability.

When forming a polyurethane prepolymer, any suitable polyol may bereacted with the above-described isocyanate blends in accordance withthis invention. Exemplary polyols include, but are not limited to,polyether polyols, hydroxy-terminated polybutadiene (includingpartially/fully hydrogenated derivatives), polyester polyols,polycaprolactone polyols, and polycarbonate polyols. In one preferredembodiment, the polyol includes polyether polyol. Examples include, butare not limited to, polytetramethylene ether glycol (PTMEG),polyethylene propylene glycol, polyoxypropylene glycol, and mixturesthereof. The hydrocarbon chain can have saturated or unsaturated bondsand substituted or unsubstituted aromatic and cyclic groups. Preferably,the polyol of the present invention includes PTMEG. In anotherembodiment, polyester polyols are included in the polyurethane material.Suitable polyester polyols include, but are not limited to, polyethyleneadipate glycol; polybutylene adipate glycol; polyethylene propyleneadipate glycol; o-phthalate-1,6-hexanediol; poly(hexamethylene adipate)glycol; and mixtures thereof. The hydrocarbon chain can have saturatedor unsaturated bonds, or substituted or unsubstituted aromatic andcyclic groups. In still another embodiment, polycaprolactone polyols areincluded in the materials of the invention. Suitable polycaprolactonepolyols include, but are not limited to: 1,6-hexanediol-initiatedpolycaprolactone, diethylene glycol initiated polycaprolactone,trimethylol propane initiated polycaprolactone, neopentyl glycolinitiated polycaprolactone, 1,4-butanediol-initiated polycaprolactone,and mixtures thereof. The hydrocarbon chain can have saturated orunsaturated bonds, or substituted or unsubstituted aromatic and cyclicgroups. In yet another embodiment, polycarbonate polyols are included inthe polyurethane material of the invention. Suitable polycarbonatesinclude, but are not limited to, polyphthalate carbonate andpoly(hexamethylene carbonate) glycol. The hydrocarbon chain can havesaturated or unsaturated bonds, or substituted or unsubstituted aromaticand cyclic groups. In one embodiment, the molecular weight of the polyolis from about 200 to about 4000.

In a manner similar to making the above-described polyurea compositions,there are two basic techniques that can be used to make the polyurethanecompositions of this invention: a) one-shot technique, and b) prepolymertechnique. In the one-shot technique, the isocyanate blend, polyol, andhydroxyl-terminated and/or amine-terminated chain-extender (curingagent) are reacted in one step. On the other hand, the prepolymertechnique involves a first reaction between the isocyanate blend andpolyol compounds to produce a polyurethane prepolymer, and a subsequentreaction between the prepolymer and hydroxyl-terminated and/oramine-terminated chain-extender. As a result of the reaction between theisocyanate and polyol compounds, there will be some unreacted NCO groupsin the polyurethane prepolymer. The prepolymer should have less than 14%unreacted NCO groups. Preferably, the prepolymer has no greater than8.5% unreacted NCO groups, more preferably from 2.5% to 8%, and mostpreferably from 5.0% to 8.0% unreacted NCO groups. As the weight percentof unreacted isocyanate groups increases, the hardness of thecomposition also generally increases.

Either the one-shot or prepolymer method may be employed to produce thepolyurethane compositions of the invention. In one embodiment, theone-shot method is used, wherein the isocyanate compound is added to areaction vessel and then a curative mixture comprising the polyol andcuring agent is added to the reaction vessel. The components are mixedtogether so that the molar ratio of isocyanate groups to hydroxyl groupsis in the range of about 1.01:1.00 to about 1.10:1.00. Preferably, themolar ratio is greater than or equal to 1.05:1.00. For example, themolar ratio can be in the range of 1.05:1.00 to 1.10:1.00. In a secondembodiment, the prepolymer method is used. In general, the prepolymertechnique is preferred because it provides better control of thechemical reaction. The prepolymer method provides a more homogeneousmixture resulting in a more consistent polymer composition. The one-shotmethod results in a mixture that is inhomogeneous (more random) andaffords the manufacturer less control over the molecular structure ofthe resultant composition.

The polyurethane compositions can be formed by chain-extending thepolyurethane prepolymer with a single curing agent (chain-extender) orblend of curing agents (chain-extenders) as described further below. Thecompositions of the present invention may be selected from among bothcastable thermoplastic and thermoset polyurethanes. Thermoplasticpolyurethane compositions are typically formed by reacting theisocyanate blend and polyols at a 1:1 stoichiometric ratio. Thermosetcompositions, on the other hand, are cross-linked polymers and aretypically produced from the reaction of the isocyanate blend and polyolsat normally a 1.05:1 stoichiometric ratio. In general, thermosetpolyurethane compositions are easier to prepare than thermoplasticpolyurethanes.

As discussed above, the polyurethane prepolymer can be chain-extended byreacting it with a single chain-extender or blend of chain-extenders. Ingeneral, the prepolymer can be reacted with hydroxyl-terminated curingagents, amine-terminated curing agents, and mixtures thereof. The curingagents extend the chain length of the prepolymer and build-up itsmolecular weight. Normally, the prepolymer and curing agent are mixed sothe isocyanate groups and hydroxyl or amine groups are mixed at a1.05:1.00 stoichiometric ratio.

A catalyst may be employed to promote the reaction between theisocyanate and polyol compounds for producing the polyurethaneprepolymer or between the polyurethane prepolymer and chain-extenderduring the chain-extending step. Preferably, the catalyst is added tothe reactants before producing the polyurethane prepolymer. Suitablecatalysts include, but are not limited to, the catalysts described abovefor making the polyurea prepolymer. The catalyst is preferably added inan amount sufficient to catalyze the reaction of the components in thereactive mixture. In one embodiment, the catalyst is present in anamount from about 0.001 percent to about 1 percent, and preferably 0.1to 0.5 percent, by weight of the composition. Suitable hydroxylchain-extending (curing) agents and amine chain-extending (curing)agents include, but are not limited to, the curing agents describedabove for making the polyurea and polyurea/urethane hybrid compositions.When the polyurethane prepolymer is reacted with hydroxyl-terminatedcuring agents during the chain-extending step, as described above, theresulting polyurethane composition contains urethane linkages. On theother hand, when the polyurethane prepolymer is reacted withamine-terminated curing agents during the chain-extending step, anyexcess isocyanate groups in the prepolymer will react with the aminegroups in the curing agent. The resulting polyurethane compositioncontains urethane and urea linkages and may be referred to as apolyurethane/urea hybrid. The concentration of urethane and urealinkages in the hybrid composition may vary. In general, the hybridcomposition may contain a mixture of about 10 to 90% urethane and about90 to 10% urea linkages.

Examples of commercially available thermoplastics suitable for formingthermoplastic layers include, but are not limited to, Pebax®thermoplastic polyether block amides, commercially available from ArkemaInc.; Surlyn® ionomer resins, Hytrel® thermoplastic polyesterelastomers, and ionomeric materials sold under the trade names DuPont®HPF 1000, HPF 2000, HPF AD 1035, HPF AD 1040, all of which arecommercially available from E. I. du Pont de Nemours and Company; Iotek®ionomers, commercially available from ExxonMobil Chemical Company;Amplify® IO ionomers of ethylene acrylic acid copolymers, commerciallyavailable from The Dow Chemical Company; Clarix® ionomer resins,commercially available from A. Schulman Inc.; Elastollan®polyurethane-based thermoplastic elastomers, commercially available fromBASF; and Xylex® polycarbonate/polyester blends, commercially availablefrom SABIC Innovative Plastics.

Suitable plasticized polymer compositions include a plasticizer in anamount sufficient to substantially change the stiffness and/or hardnessof the composition, and typically comprise from 20 to 99.5 wt % of thepolymer and from 0.5 to 80 wt % of the plasticizer, based on thecombined weight of the polymer and the plasticizer. In a particularembodiment, the plasticizer is present in an amount of 0.5% or 1% or 3%or 5% or 7% or 8% or 9% or 10% or 12% or 15% or 18% or 20% or 22% or 25%or 30% or 35% or 40% or 42% or 50% or 55% or 60% or 66% or 71% or 75% or80%, by weight based on the combined weight of the polymer and theplasticizer, or the plasticizer is present in an amount within a rangehaving a lower limit and an upper limit selected from these values.Suitable polymers include acid copolymers, partially neutralized acidcopolymers, highly neutralized acid polymers (“HNPs”), polyesters,polyamides, thermosetting and thermoplastic polyurethanes.

Suitable plasticized acid copolymer compositions, plasticized partiallyneutralized acid copolymer compositions, and plasticized HNPcompositions, and particularly suitable golf ball constructionsutilizing such compositions, are further disclosed, for example, in U.S.Patent Application Publ. No. 2015/0031475, U.S. Patent Application Publ.No. 2015/0005108, U.S. patent application Ser. No. 14/576,800, and U.S.patent application Ser. No. 14/588,317, the entire disclosures of whichare hereby incorporated herein by reference.

Suitable plasticized polyester compositions, and particularly suitablegolf ball constructions utilizing such compositions, are furtherdisclosed, for example, in U.S. patent application Ser. No. 14/532,141,the entire disclosure of which is hereby incorporated herein byreference.

Suitable plasticized polyamide compositions, and particularly suitablegolf ball constructions utilizing such compositions, are furtherdisclosed, for example, in U.S. Patent Application Publ. No.2014/0302947, U.S. Patent Application Publ. No. 2014/0323243, U.S.Patent Application Publ. No. 20150057105, and U.S. patent applicationSer. No. 14/576,324, the entire disclosures of which are herebyincorporated herein by reference.

Suitable plasticized polyurethane compositions, and particularlysuitable golf ball constructions utilizing such compositions, arefurther disclosed, for example, in U.S. patent application Ser. No.14/672,538, U.S. patent application Ser. No. 14/672,523, U.S. patentapplication Ser. No. 14/672,485, and U.S. patent application Ser. No.14/691,720, the entire disclosures of which are hereby incorporatedherein by reference. Further suitable plasticized compositions includefor example those disclosed in U.S. patent application Ser. Nos.14/571,610, 14/576,324, and 14/707,028.

And it is contemplated that a golf ball of the invention may have anyknown construction and have any number of layers with any knownproperties with the foremost limitation being a high or steep hardnessgradient in the core as discussed herein.

The core may have a dual core arrangement having a total diameter offrom about 1.40 in. to about 1.65 in, for example, wherein the innercore may has a diameter of from about 0.75 inches to about 1.30 in. andthe outer core has a thickness of from about 0.05 in. to about 0.45 in.Cover thicknesses generally range from about 0.015 in. to about 0.090inches, although a golf ball of the invention may comprise any knownthickness. Meanwhile, casing layers and inner cover layers eachtypically have thicknesses ranging from about 0.01 in. to about 0.06 in.A golf ball of the invention may also have one or more film layers,paint layers or coating layers having a combined thickness of from about0.1 μm to about 100 μm, or from about 2 μm to about 50 μm, or from about2 μm to about 30 μm. Meanwhile, each coating layer may have a thicknessof from about 0.1 μm to about 50 μm, or from about 0.1 μm to about 25μm, or from about 0.1 μm to about 14 μm, or from about 2 μm to about 9μm, for example.

In some embodiments, the core may have an overall diameter within arange having a lower limit of 0.500 or 0.700 or 0.750 or 0.800 or 0.850or 0.900 or 0.950 or 1.000 or 1.100 or 1.150 or 1.200 or 1.250 or 1.300or 1.350 or 1.400 or 1.450 or 1.500 or 1.600 or 1.610 inches and anupper limit of 1.620 or 1.630 or 1.640 inches. In a particularembodiment, the core is a multi-layer core having an overall diameterwithin a range having a lower limit of 0.500 or 0.700 or 0.750 or 0.800or 0.850 or 0.900 or 0.950 or 1.000 or 1.100 or 1.150 or 1.200 inchesand an upper limit of 1.250 or 1.300 or 1.350 or 1.400 or 1.450 or 1.500or 1.600 or 1.610 or 1.620 or 1.630 or 1.640 inches. In anotherparticular embodiment, the multi-layer core has an overall diameterwithin a range having a lower limit of 0.500 or 0.700 or 0.750 inchesand an upper limit of 0.800 or 0.850 or 0.900 or 0.950 or 1.000 or 1.100or 1.150 or 1.200 or 1.250 or 1.300 or 1.350 or 1.400 or 1.450 or 1.500or 1.600 or 1.610 or 1.620 or 1.630 or 1.640 inches. In anotherparticular embodiment, the multi-layer core has an overall diameter of1.500 inches or 1.510 inches or 1.530 inches or 1.550 inches or 1.570inches or 1.580 inches or 1.590 inches or 1.600 inches or 1.610 inchesor 1.620 inches.

The inner core can have an overall diameter of 0.500 inches or greater,or 0.700 inches or greater, or 1.00 inches or greater, or 1.250 inchesor greater, or 1.350 inches or greater, or 1.390 inches or greater, or1.450 inches or greater, or an overall diameter within a range having alower limit of 0.250 or 0.500 or 0.750 or 1.000 or 1.250 or 1.350 or1.390 or 1.400 or 1.440 inches and an upper limit of 1.460 or 1.490 or1.500 or 1.550 or 1.580 or 1.600 inches, or an overall diameter within arange having a lower limit of 0.250 or 0.300 or 0.350 or 0.400 or 0.500or 0.550 or 0.600 or 0.650 or 0.700 inches and an upper limit of 0.750or 0.800 or 0.900 or 0.950 or 1.000 or 1.100 or 1.150 or 1.200 or 1.250or 1.300 or 1.350 or 1.400 inches. In one embodiment, the inner coreconsists of a single layer formed from a thermoset rubber composition.In another embodiment, the inner core consists of two layers, each ofwhich is formed from the same or different thermoset rubbercompositions. In another embodiment, the inner core comprises three ormore layers, each of which is formed from the same or differentthermoset rubber compositions. In another embodiment, the inner coreconsists of a single layer formed from a thermoplastic composition. Inanother embodiment, the inner core consists of two layers, each of whichis formed from the same or different thermoplastic compositions. Inanother embodiment, the inner core comprises three or more layers, eachof which is formed from the same or different thermoplasticcompositions.

In a particular embodiment, the overall core of a golf ball of theinvention has one or more of the following properties:

-   a) a geometric center hardness within a range having a lower limit    of 20 or 25 or 30 or 35 or 40 or 45 or 50 or 55 Shore C and an upper    limit of 60 or 65 or 70 or 75 or less than about 79 Shore C;-   b) an outer surface hardness within a range having a lower limit of    80 or 85 or 90 or 95 Shore C;-   c) a positive hardness gradient of at least 20 Shore C; and-   d) an overall compression of about 75 or greater, or greater than    75, or about 80 or greater, or greater than or 80.

An intermediate core layer can have an overall thickness within a rangehaving a lower limit of 0.005 or 0.010 or 0.015 or 0.020 or 0.025 or0.030 or 0.035 or 0.040 or 0.045 inches and an upper limit of 0.050 or0.055 or 0.060 or 0.065 or 0.070 or 0.075 or 0.080 or 0.090 or 0.100inches. In one embodiment, the intermediate core consists of a singlelayer formed from a thermoset rubber composition. In another embodiment,the intermediate core consists of two layers, each of which is formedfrom the same or different thermoset rubber compositions. In anotherembodiment, the intermediate core comprises three or more layers, eachof which is formed from the same or different thermoset rubbercompositions. In another embodiment, the intermediate core consists of asingle layer formed from a thermoplastic composition. In anotherembodiment, the intermediate core consists of two layers, each of whichis formed from the same or different thermoplastic compositions. Inanother embodiment, the intermediate core comprises three or morelayers, each of which is formed from the same or different thermoplasticcompositions.

The outer core layer can have an overall thickness within a range havinga lower limit of 0.010 or 0.020 or 0.025 or 0.030 or 0.035 inches and anupper limit of 0.040 or 0.070 or 0.075 or 0.080 or 0.100 or 0.150inches, or an overall thickness within a range having a lower limit of0.025 or 0.050 or 0.100 or 0.150 or 0.160 or 0.170 or 0.200 inches andan upper limit of 0.225 or 0.250 or 0.275 or 0.300 or 0.325 or 0.350 or0.400 or 0.450 or greater than 0.450 inches. The outer core layer mayalternatively have a thickness of greater than 0.10 inches, or 0.20inches or greater, or greater than 0.20 inches, or 0.30 inches orgreater, or greater than 0.30 inches, or 0.35 inches or greater, orgreater than 0.35 inches, or 0.40 inches or greater, or greater than0.40 inches, or 0.45 inches or greater, or greater than 0.45 inches, ora thickness within a range having a lower limit of 0.005 or 0.010 or0.015 or 0.020 or 0.025 or 0.030 or 0.035 or 0.040 or 0.045 or 0.050 or0.055 or 0.060 or 0.065 or 0.070 or 0.075 or 0.080 or 0.090 or 0.100 or0.200 or 0.250 inches and an upper limit of 0.300 or 0.350 or 0.400 or0.450 or 0.500 inches or greater.

It is envisioned that the outer core layer may have more than one layer,as long as each of the layers forming the outer core layer consist of amixture of a plurality of synthetic flocks and a first thermoset rubbercomposition; with the plurality of synthetic flocks has a meltingtemperature that is greater than a mixing temperature at which themixture is formed; and the outer core layer as a whole has an outermostsurface having an outer surface hardness of about 80 Shore C or greater;that is greater than a center hardness of the geometric center of thecore by at least 20 Shore C. Of course, it is also envisioned that in amulti-layered outer core layer, each core layer thereforming may consistof a different mixture of a plurality of synthetic flocks and a firstthermoset rubber composition. For example, in one embodiment, the outercore layer may have two differing layers, an inner layer that differsfrom an outer layer only by the type of flock mixed (e.g., the innerlayer may contain nylon flocks whereas the outer layer containspolyester flocks). Or, the inner layer and outer layer may contain thesame flocks but in differing amounts (phr) thereof. Additionally oralternatively, the inner and outer layers may include differingthermoset rubber compositions. And in different embodiments, the outercore layer may have three or more layers, some or all of which differwith respect to the type of flock used and/or the particular thermosetrubber composition included in the mixture.

The outer core layer may meanwhile have any thickness known in the artfor outer core layers.

And it is recognized that a layer consisting of the mixture of aplurality of synthetic flocks and a thermoset rubber composition mayalso be useful for targeting other desired golf ball properties whenused in different layers such as in an intermediate core layer that isdisposed between an inner core layer and an outer core layer forexample. In such an embodiment the intermediate core layer consists ofthe mixture of a plurality of synthetic flocks and a thermoset rubbercomposition; with the plurality of synthetic flocks having a meltingtemperature that is greater than a mixing temperature at which themixture is formed; and the intermediate core layer having an outersurface with an outer surface hardness of about 80 Shore C or greaterand greater than the hardness of the geometric center of the core by atleast 20 Shore C. In this embodiment, the outer core layer might beformed from any known material such as a thermoplastic composition.

The multi-layer core is enclosed with a cover, which may be a single-,dual-, or multi-layer cover, preferably having an overall thicknesswithin a range having a lower limit of 0.010 or 0.020 or 0.025 or 0.030or 0.040 or 0.045 inches and an upper limit of 0.050 or 0.060 or 0.070or 0.075 or 0.080 or 0.090 or 0.100 or 0.150 or 0.200 or 0.300 or 0.500inches. In a particular embodiment, the cover is a single layer having athickness of from 0.010 or 0.020 or 0.025 inches to 0.035 or 0.040 or0.050 inches. In another particular embodiment, the cover consists of aninner cover layer having a thickness of from 0.010 or 0.020 or 0.025inches to 0.035 or 0.050 inches and an outer cover layer having athickness of from 0.010 or 0.020 or 0.025 inches to 0.035 or 0.040inches.

In one embodiment, the cover is a single layer having a surface hardnessof 60 Shore D or greater, or 65 Shore D or greater. In a particularaspect of this embodiment, the cover is formed from a composition havinga material hardness of 60 Shore D or greater, or 65 Shore D or greater.

In another particular embodiment, the cover is a single layer having athickness of from 0.010 or 0.020 inches to 0.035 or 0.050 inches andformed from an ionomeric composition having a material hardness of from60 or 62 or 65 Shore D to 65 or 70 or 72 Shore D.

In another particular embodiment, the cover is a single layer having athickness of from 0.010 or 0.025 inches to 0.035 or 0.040 inches andformed from a thermoplastic composition selected from ionomer-,polyurethane-, and polyurea-based compositions having a materialhardness of 62 Shore D or less, or less than 62 Shore D, or 60 Shore Dor less, or less than 60 Shore D, or 55 Shore D or less, or less than 55Shore D.

In another particular embodiment, the cover is a single layer having athickness of from 0.010 or 0.025 inches to 0.035 or 0.040 inches andformed from a thermosetting polyurethane- or polyurea-based compositionhaving a material hardness of 62 Shore D or less, or less than 62 ShoreD, or 60 Shore D or less, or less than 60 Shore D, or 55 Shore D orless, or less than 55 Shore D.

In another particular embodiment, the cover comprises an inner coverlayer formed from an ionomeric composition and an outer cover layerformed from a thermosetting polyurethane- or polyurea-based composition.The inner cover layer composition preferably has a material hardness offrom 60 or 62 or 65 Shore D to 65 or 70 or 72 Shore D. The inner coverlayer preferably has a thickness within a range having a lower limit of0.010 or 0.020 or 0.030 inches and an upper limit of 0.035 or 0.040 or0.050 inches. The outer cover layer composition preferably has amaterial hardness of 62 Shore D or less, or less than 62 Shore D, or 60Shore D or less, or less than 60 Shore D, or 55 Shore D or less, or lessthan 55 Shore D. The outer cover layer preferably has a thickness withina range having a lower limit of 0.010 or 0.020 or 0.025 inches and anupper limit of 0.035 or 0.040 or 0.050 inches.

In another particular embodiment, the cover comprises an inner coverlayer formed from an ionomeric composition and an outer cover layerformed from a thermoplastic composition selected from ionomer-,polyurethane-, and polyurea-based compositions. The inner cover layercomposition preferably has a material hardness of from 60 or 62 or 65Shore D to 65 or 70 or 72 Shore D. The inner cover layer preferably hasa thickness within a range having a lower limit of 0.010 or 0.020 or0.030 inches and an upper limit of 0.035 or 0.040 or 0.050 inches. Theouter cover layer composition preferably has a material hardness of 62Shore D or less, or less than 62 Shore D, or 60 Shore D or less, or lessthan 60 Shore D, or 55 Shore D or less, or less than 55 Shore D. Theouter cover layer preferably has a thickness within a range having alower limit of 0.010 or 0.020 or 0.025 inches and an upper limit of0.035 or 0.040 or 0.050 inches.

In another particular embodiment, the cover is a dual- or multi-layercover including an inner or intermediate cover layer formed from anionomeric composition and an outer cover layer formed from apolyurethane- or polyurea-based composition. The ionomeric layerpreferably has a surface hardness of 70 Shore D or less, or 65 Shore Dor less, or less than 65 Shore D, or a Shore D hardness of from 50 to65, or a Shore D hardness of from 57 to 60, or a Shore D hardness of 58,and a thickness within a range having a lower limit of 0.010 or 0.020 or0.030 inches and an upper limit of 0.045 or 0.080 or 0.120 inches. Theouter cover layer is preferably formed from a castable or reactioninjection moldable polyurethane, polyurea, or copolymer or hybrid ofpolyurethane/polyurea. Such cover material is preferably thermosetting,but may be thermoplastic. The outer cover layer composition preferablyhas a material hardness of 85 Shore C or less, or 45 Shore D or less, or40 Shore D or less, or from 25 Shore D to 40 Shore D, or from 30 Shore Dto 40 Shore D. The outer cover layer preferably has a surface hardnesswithin a range having a lower limit of 20 or 30 or 35 or 40 Shore D andan upper limit of 52 or 58 or 60 or 65 or 70 or 72 or 75 Shore D. Theouter cover layer preferably has a thickness within a range having alower limit of 0.010 or 0.015 or 0.025 inches and an upper limit of0.035 or 0.040 or 0.045 or 0.050 or 0.055 or 0.075 or 0.080 or 0.115inches.

In another particular embodiment, the cover comprises an inner coverlayer formed from an ionomeric composition and an outer cover layerformed from a thermosetting polyurethane- or polyurea-based composition.The inner cover layer composition preferably has a material hardness offrom 60 or 62 or 65 Shore D to 65 or 70 or 72 Shore D. The inner coverlayer preferably has a thickness within a range having a lower limit of0.010 or 0.020 or 0.030 inches and an upper limit of 0.035 or 0.040 or0.050 inches. The outer cover layer composition preferably has amaterial hardness of 62 Shore D or less, or less than 62 Shore D, or 60Shore D or less, or less than 60 Shore D, or 55 Shore D or less, or lessthan 55 Shore D. The outer cover layer preferably has a thickness withina range having a lower limit of 0.010 or 0.020 or 0.025 inches and anupper limit of 0.035 or 0.040 or 0.050 inches.

In another particular embodiment, the cover comprises an inner coverlayer formed from an ionomeric composition and an outer cover layerformed from a thermoplastic composition selected from ionomer-,polyurethane-, and polyurea-based compositions. The inner cover layercomposition preferably has a material hardness of from 60 or 62 or 65Shore D to 65 or 70 or 72 Shore D. The inner cover layer preferably hasa thickness within a range having a lower limit of 0.010 or 0.020 or0.030 inches and an upper limit of 0.035 or 0.040 or 0.050 inches. Theouter cover layer composition preferably has a material hardness of 62Shore D or less, or less than 62 Shore D, or 60 Shore D or less, or lessthan 60 Shore D, or 55 Shore D or less, or less than 55 Shore D. Theouter cover layer preferably has a thickness within a range having alower limit of 0.010 or 0.020 or 0.025 inches and an upper limit of0.035 or 0.040 or 0.050 inches.

In another particular embodiment, the cover is a dual- or multi-layercover including an inner or intermediate cover layer formed from anionomeric composition and an outer cover layer formed from apolyurethane- or polyurea-based composition. The ionomeric layerpreferably has a surface hardness of 70 Shore D or less, or 65 Shore Dor less, or less than 65 Shore D, or a Shore D hardness of from 50 to65, or a Shore D hardness of from 57 to 60, or a Shore D hardness of 58,and a thickness within a range having a lower limit of 0.010 or 0.020 or0.030 inches and an upper limit of 0.045 or 0.080 or 0.120 inches. Theouter cover layer is preferably formed from a castable or reactioninjection moldable polyurethane, polyurea, or copolymer or hybrid ofpolyurethane/polyurea. Such cover material is preferably thermosetting,but may be thermoplastic. The outer cover layer composition preferablyhas a material hardness of 85 Shore C or less, or 45 Shore D or less, or40 Shore D or less, or from 25 Shore D to 40 Shore D, or from 30 Shore Dto 40 Shore D. The outer cover layer preferably has a surface hardnesswithin a range having a lower limit of 20 or 30 or 35 or 40 Shore D andan upper limit of 52 or 58 or 60 or 65 or 70 or 72 or 75 Shore D. Theouter cover layer preferably has a thickness within a range having alower limit of 0.010 or 0.015 or 0.025 inches and an upper limit of0.035 or 0.040 or 0.045 or 0.050 or 0.055 or 0.075 or 0.080 or 0.115inches.

The compressions and CoRs of each golf ball layer may meanwhile also betargeted and coordinated with each other to form an overall golf ballpossessing/displaying desired playing characteristics.

For purposes of the present invention, “compression” refers to Atticompression and is measured according to a known procedure, using anAtti compression test device, wherein a piston is used to compress aball against a spring. The travel of the piston is fixed and thedeflection of the spring is measured. The measurement of the deflectionof the spring does not begin with its contact with the ball; rather,there is an offset of approximately the first 1.25 mm (0.05 inches) ofthe spring's deflection. Very low compression cores will not cause thespring to deflect by more than 1.25 mm and therefore have a zero ornegative compression measurement. The Atti compression tester isdesigned to measure objects having a diameter of 1.680 inches; thus,smaller objects, such as golf ball cores, must be shimmed to a totalheight of 1.680 inches to obtain an accurate reading. Conversion fromAtti compression to Riehle (cores), Riehle (balls), 100 kg deflection,130-10 kg deflection or effective modulus can be carried out accordingto the formulas given in Compression by Any Other Name, Science and GolfIV, Proceedings of the World Scientific Congress of Golf (Eric Thained., Routledge, 2002).

CoR, as used herein, is determined according to a known procedurewherein a sphere is fired from an air cannon at two given velocities andcalculated at a velocity of 125 ft/s. Ballistic light screens arelocated between the air cannon and the steel plate at a fixed distanceto measure ball velocity. As the sphere travels toward the steel plate,it activates each light screen, and the time at each light screen ismeasured. This provides an incoming transit time period inverselyproportional to the sphere's incoming velocity. The sphere impacts thesteel plate and rebounds through the light screens, which again measuresthe time period required to transit between the light screens. Thisprovides an outgoing transit time period inversely proportional to thesphere's outgoing velocity. CoR is then calculated as the ratio of theoutgoing transit time period to the incoming transit time period,CoR=V_(out)/V_(in)=T_(in)/T_(out). For example, the CoR value can betargeted in a thermoset rubber core by varying peroxide and antioxidanttypes and amounts as well as the cure temperature and duration.

The center hardness of a core is obtained according to the followingprocedure. The core is gently pressed into a hemispherical holder havingan internal diameter approximately slightly smaller than the diameter ofthe core, such that the core is held in place in the hemisphericalportion of the holder while concurrently leaving the geometric centralplane of the core exposed. The core is secured in the holder byfriction, such that it will not move during the cutting and grindingsteps, but the friction is not so excessive that distortion of thenatural shape of the core would result. The core is secured such thatthe parting line of the core is roughly parallel to the top of theholder. The diameter of the core is measured 90 degrees to thisorientation prior to securing. A measurement is also made from thebottom of the holder to the top of the core to provide a reference pointfor future calculations. A rough cut is made slightly above the exposedgeometric center of the core using a band saw or other appropriatecutting tool, making sure that the core does not move in the holderduring this step. The remainder of the core, still in the holder, issecured to the base plate of a surface grinding machine. The exposed‘rough’ surface is ground to a smooth, flat surface, revealing thegeometric center of the core, which can be verified by measuring theheight from the bottom of the holder to the exposed surface of the core,making sure that exactly half of the original height of the core, asmeasured above, has been removed to within ±0.004 inches. Leaving thecore in the holder, the center of the core is found with a center squareand carefully marked and the hardness is measured at the center markaccording to ASTM D-2240. Additional hardness measurements at anydistance from the center of the core can then be made by drawing a lineradially outward from the center mark, and measuring the hardness at anygiven distance along the line, typically in 2 mm increments from thecenter. The hardness at a particular distance from the center should bemeasured along at least two, preferably four, radial arms located 180°apart, or 90° apart, respectively, and then averaged. All hardnessmeasurements performed on a plane passing through the geometric centerare performed while the core is still in the holder and without havingdisturbed its orientation, such that the test surface is constantlyparallel to the bottom of the holder, and thus also parallel to theproperly aligned foot of the durometer.

Hardness points should only be measured once at any particular geometriclocation.

The surface hardness of a golf ball layer is obtained from the averageof a number of measurements taken from opposing hemispheres, taking careto avoid making measurements on the parting line of the core or onsurface defects such as holes or protrusions. Hardness measurements aremade pursuant to ASTM D-2240 “Indentation Hardness of Rubber and Plasticby Means of a Durometer.” Because of the curved surface of the golf balllayer, care must be taken to ensure that the golf ball or golf ballsubassembly is centered under the durometer indentor before a surfacehardness reading is obtained. A calibrated digital durometer, capable ofreading to 0.1 hardness units, is used for all hardness measurements.The digital durometer must be attached to and its foot made parallel tothe base of an automatic stand. The weight on the durometer and attackrate conforms to ASTM D-2240. It should be understood that there is afundamental difference between “material hardness” and “hardness asmeasured directly on a golf ball.” For purposes of the presentinvention, material hardness is measured according to ASTM D2240 andgenerally involves measuring the hardness of a flat “slab” or “button”formed of the material. Surface hardness as measured directly on a golfball (or other spherical surface) typically results in a differenthardness value. The difference in “surface hardness” and “materialhardness” values is due to several factors including, but not limitedto, ball construction (that is, core type, number of cores and/or coverlayers, and the like); ball (or sphere) diameter; and the materialcomposition of adjacent layers. It also should be understood that thetwo measurement techniques are not linearly related and, therefore, onehardness value cannot easily be correlated to the other.

It should be understood that there is a fundamental difference between“material hardness” and “hardness as measured directly on a golf ball.”For purposes of the present disclosure, material hardness is measuredaccording to ASTM D2240 and generally involves measuring the hardness ofa flat “slab” or “button” formed of the material. Hardness as measureddirectly on a golf ball (or other spherical surface) typically resultsin a different hardness value. This difference in hardness values is dueto several factors including, but not limited to, ball construction(i.e., core type, number of core and/or cover layers, etc.), ball (orsphere) diameter, and the material composition of adjacent layers. Itshould also be understood that the two measurement techniques are notlinearly related and, therefore, one hardness value cannot easily becorrelated to the other.

It is understood that the golf balls of the invention incorporating atleast one core layer consisting of a mixture of a plurality of syntheticflocks and a thermoset rubber composition, as described and illustratedherein, represent only some of the many embodiments of the invention. Itis appreciated by those skilled in the art that various changes andadditions can be made to such golf balls without departing from thespirit and scope of this invention. It is intended that all suchembodiments be covered by the appended claims.

A golf ball of the invention may further incorporate indicia, which asused herein, is considered to mean any symbol, letter, group of letters,design, or the like, that can be added to the dimpled surface of a golfball.

It will be appreciated that any known dimple pattern may be used withany number of dimples having any shape or size. For example, the numberof dimples may be 252 to 456, or 330 to 392 and may comprise any width,depth, and edge angle. The parting line configuration of said patternmay be either a straight line or a staggered wave parting line (SWPL),for example.

And the cover hardness and the hardness of any intermediate layers maybe targeted depending on desired playing characteristics. As a generalrule, all other things being equal, a golf ball having a relatively softcover will spin more than a similarly constructed ball having a hardercover.

Other than in the operating examples, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentagessuch as those for amounts of materials and others in the specificationmay be read as if prefaced by the word “about” even though the term“about” may not expressly appear with the value, amount or range.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the specification and attached claims are approximationsthat may vary depending upon the desired properties sought to beobtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

Although the golf ball of the invention has been described herein withreference to particular means and materials, it is to be understood thatthe invention is not limited to the particulars disclosed and extends toall equivalents within the scope of the claims.

When numerical lower limits and numerical upper limits are set forthherein, it is contemplated that any combination of these values may beused.

All patents, publications, test procedures, and other references citedherein, including priority documents, are fully incorporated byreference to the extent such disclosure is not inconsistent with thisinvention and for all jurisdictions in which such incorporation ispermitted.

While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by those ofordinary skill in the art without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the examples and descriptions setforth herein, but rather that the claims be construed as encompassingall of the features of patentable novelty which reside in the presentinvention, including all features which would be treated as equivalentsthereof by those of ordinary skill in the art to which the inventionpertains.

What is claimed is:
 1. A golf ball comprising: a core comprising aninner core layer and an outer core layer; wherein the outer core layerconsists of a mixture of a plurality of synthetic flocks and a firstthermoset rubber composition; wherein the plurality of synthetic flockshas a melting temperature that is greater than a mixing temperature atwhich the mixture is formed; and wherein the outer core layer comprisesan outer surface having an outer surface hardness of about 80 Shore C orgreater; and wherein the outer surface hardness is greater than a centerhardness of a geometric center of the core by at least 20 Shore C; and acover having one or more layers disposed about the core.
 2. The golfball of claim 1, wherein the synthetic flocks are included in themixture in an amount of from about 0.5 parts to about 15 parts of thetotal mixture.
 3. The golf ball of claim 2, wherein the synthetic flocksare selected from the group consisting of nylon flocks, polyesterflocks, or a combinations thereof.
 4. The golf ball of claim 1, whereinthe first thermoset rubber composition comprises polybutadiene.
 5. Thegolf ball of claim 4, wherein the first thermoset rubber compositioncomprises a blend of the polybutadiene and at least one ofpolyoctenemer, natural rubber, ethylene propylene diene monomer (EPDM),cis-polyisoprene, trans-polyisioprene, and styrene-butadiene rubber(SBR).
 6. The golf ball of claim 1, wherein the first thermoset rubbercomposition is formed from at least one rubber and at least one of zincoxide, reactive coagent(s), peroxide(s), soft and fast agent(s), fattyacid(s)/fatty acid salt(s), inorganic filler(s), antioxidant(s), andantiozonants.
 7. The golf ball of claim 1, wherein the outer core layersurrounds and is adjacent to the inner core layer.
 8. The golf ball ofclaim 1, wherein the outer core layer has a compression of greater than72.
 9. The golf ball of claim 1, wherein the outer core layer has acompression of 75 or greater.
 10. The golf ball of claim 8, wherein theouter surface hardness is greater than 82 Shore C.
 11. The golf ball ofclaim 1, wherein the outer surface hardness is greater than 85 Shore C.12. The golf ball of claim 1, wherein the outer surface hardness isabout 90 Shore C or greater and is greater than the center hardness bygreater than 30 Shore C.
 13. The golf ball of claim 8, wherein the innercore layer consists of a thermoset composition.
 14. The golf ball ofclaim 13, wherein the thermoset composition is different than the firstthermoset rubber composition.
 15. The golf ball of claim 8, wherein theinner core layer consists of a thermoplastic composition.
 16. The golfball of claim 15, wherein the thermoplastic composition comprises anionomer.
 17. The golf ball of claim 15, wherein the thermoplasticcomposition comprises a polyether-ester, a polyester-amide, or blendsthereof.
 18. The golf ball of claim 1, wherein an intermediate corelayer is disposed between the inner core layer and the outer core layer.19. The golf ball of claim 18, wherein the intermediate core layercomprises a thermoplastic composition.
 20. The golf ball of claim 1,wherein the cover comprises an inner cover layer disposed about theouter core layer and comprising an ionomeric material and having a firsthardness; and an outer cover layer disposed about the inner cover layerand comprising a polyurea or a polyurethane and having a second hardnessless than the first.
 21. The golf ball of claim 1, wherein each of theplurality of synthetic flocks has a length in the range of about 0.004inches to about 0.2 inches.
 22. The golf ball of claim 1, wherein eachof the plurality of synthetic flocks has a length in the range of about0.02 inches to about 0.08 inches.
 23. The golf ball of claim 1, whereineach of the plurality of synthetic flocks has a length in the range ofabout 0.02 inches to about 0.04 inches.
 24. A golf ball comprising: acore comprising at least one layer that consists of a mixture of aplurality of synthetic flocks and a thermoset rubber composition;wherein the plurality of synthetic flocks has a melting temperature thatis greater than a mixing temperature at which the mixture is formed; andwherein the at least one layer comprises an outer surface having anouter surface hardness of about 80 Shore C or greater; and wherein theouter surface hardness is greater than a center hardness of a geometriccenter of the core by at least 20 Shore C; and a cover disposed aboutthe core.
 25. The golf ball of claim 24, wherein the synthetic flocksare selected from the group consisting of nylon flocks, polyesterflocks, or combinations thereof.
 26. The golf ball of claim 24, whereinthe at least one layer has a compression of greater than
 72. 27. Thegolf ball of claim 24, wherein the at least one layer has a compressionof at least
 75. 28. The golf ball of claim 24, wherein each of theplurality of synthetic flocks has a length in the range of about 0.004inches to about 0.2 inches.
 29. The golf ball of claim 24, wherein eachof the plurality of synthetic flocks has a length in the range of about0.02 inches to about 0.08 inches.
 30. The golf ball of claim 24, whereineach of the plurality of synthetic flocks has a length in the range ofabout 0.02 inches to about 0.04 inches.
 31. The golf ball of claim 26,wherein the outer surface hardness is greater than 82 Shore C.
 32. Thegolf ball of claim 24, wherein the outer surface hardness is greaterthan 85 Shore C.